Update the CLI reference for Elastic Agent (#22289) (#22397)

* Update the CLI reference

* Add changes from review

x-pack/elastic-agent/docs/elastic-agent-command-line.asciidoc

@@ -15,9 +15,15 @@ beta[]
 * <<elastic-agent-enroll-command,enroll>>
 * <<elastic-agent-help-command,help>>
 * <<elastic-agent-inspect-command,inspect>>
+* <<elastic-agent-install-command,install>>
+* <<elastic-agent-restart-command,restart>>
 * <<elastic-agent-run-command,run>>
+* <<elastic-agent-uninstall-command,uninstall>>
+* <<elastic-agent-upgrade-command,upgrade>>
 * <<elastic-agent-version-command,version>>
 
+NOTE: You might need to log in as a root user to run these commands.
+
 ++++
 <hr>
 ++++
@@ -39,7 +45,7 @@ overwrites the `elastic-agent.yml` file in the agent directory.
 ----
 elastic-agent enroll <kibana_url> <enrollment_token> [--ca-sha256 <string>]
                      [--certificate-authorities <string>] [--force] [--help]
-                     [--insecure][global-flags]
+                     [--insecure] [global-flags]
 ----
 
 [discrete]
@@ -60,7 +66,7 @@ verification.
 Comma-separated list of root certificates used for server verification.
 
 `--force`::
-Force overwrite of current policy without prompting for confirmation.
+Force overwrite of current configuration without prompting for confirmation.
 This flag is helpful when using automation software or scripted deployments.
 
 `--help`::
@@ -125,9 +131,9 @@ elastic-agent help enroll
 [[elastic-agent-inspect-command]]
 == elastic-agent inspect
 
-Show the current {agent} policy.
+Show the current {agent} configuration.
 
-If no parameters are specified, shows the full {agent} policy.
+If no parameters are specified, shows the full {agent} configuration.
 
 [discrete]
 === Synopsis
@@ -139,13 +145,10 @@ elastic-agent inspect output [--output <string>] [--program <string>]
                              [--help] [global-flags]
 ----
 
-
-//TODO: Clarify what these commands return.
-
 [discrete]
 === Options
 
-`output`:: Display the current policy for the output. This command
+`output`:: Display the current configuration for the output. This command
 accepts additional flags:
 +
 --
@@ -176,6 +179,106 @@ elastic-agent inspect output --output default --program filebeat
 <hr>
 ++++
 
+[discrete]
+[[elastic-agent-install-command]]
+== elastic-agent install
+
+Install {agent} permanently on the system and manage it by using the system's
+service manager. The agent will start automatically after installation is
+complete.
+
+You must run this command as the root user (or Administrator on Windows)
+to write files to the correct locations. This command overwrites the
+`elastic-agent.yml` file in the agent directory.
+
+[discrete]
+=== Synopsis
+
+[source,shell]
+----
+elastic-agent install [--ca-sha256 <string>] [--certificate-authorities <string>]
+                      [--enrollment-token <string>] [--force] [--help]
+                      [--insecure] [--kibana-url <string>]
+                      [global-flags]
+----
+
+[discrete]
+=== Options
+
+`--ca-sha256 <string>`::
+Comma-separated list of certificate authority hash pins used for certificate
+verification.
+
+`--certificate-authorities <string>`::
+Comma-separated list of root certificates used for server verification.
+
+`--enrollment-token <string>`::
+Enrollment token generated by {fleet}. You can use the same enrollment token for
+multiple agents.
+
+`--force`::
+Force overwrite of current configuration without prompting for confirmation.
+This flag is helpful when using automation software or scripted deployments.
+
+`--help`::
+Show help for the `install` command.
+
+`--insecure`::
+Allow an insecure connection to {kib}. When this flag is specified, API keys are
+sent in clear text. We strongly recommend that you use a secure connection.
+
+`--kibana-url <string>`::
+URL of the {kib} endpoint where {fleet} is running.
+
+{global-flags-link}
+
+[discrete]
+=== Examples
+
+[source,shell]
+----
+elastic-agent install -f --kibana-url=https://yourhost:5601 \
+  --enrollment-token=OEV0bmauVUI0a3dmdWc1T3Bad1o6VGxCa3U4UEFTQ0NycbBSUFwoazVBdx==
+----
+
+++++
+<hr>
+++++
+
+[discrete]
+[[elastic-agent-restart-command]]
+== elastic-agent restart
+
+Restart the currently running Elastic Agent daemon.
+
+[discrete]
+=== Synopsis
+
+[source,shell]
+----
+elastic-agent restart [--help] [global-flags]
+----
+
+[discrete]
+=== Options
+
+`--help`::
+Show help for the `restart` command.
+
+{global-flags-link}
+
+[discrete]
+=== Examples
+
+[source,shell]
+----
+elastic-agent restart
+----
+
+++++
+<hr>
+++++
+
 [discrete]
 [[elastic-agent-run-command]]
 == elastic-agent run
@@ -197,30 +300,22 @@ elastic-agent run [global-flags]
 These flags are valid whenever you run `elastic-agent` on the command line.
 
 `-c <string>`::
-The policy file to use. If not specified, {agent} uses
-`{path.home}/elastic-agent.yml`.
+The configuration file to use. If not specified, {agent} uses
+`{path.config}/elastic-agent.yml`.
 
 `--e`::
 Log to stderr and disable syslog/file output.
 
 `--environment <environmentVar>`::
 The environment in which the agent will run.
 
-//TODO: Clarify what we mean by environment by showing an example.
-
 `--path.config <string>`::
-The directory where {agent} looks for its policy file. The default
+The directory where {agent} looks for its configuration file. The default
 varies by platform.
 
-`--path.data <string>`::
-The data directory where {agent} stores managed binaries and their logs. Also
-stores logs for any programs started and managed by {agent}.
-+
-If not specified, {agent} uses `{path.home}/data`.
-
 `--path.home <string>`::
-The home directory of {agent}. `path.home` determines the location of the
-policy files and data directory.
+The root directory of {agent}. `path.home` determines the location of the
+configuration files and data directory.
 +
 If not specified, {agent} uses the current working directory.
 
@@ -235,7 +330,89 @@ Set log level to INFO.
 
 [source,shell]
 ----
-elastic-agent run -v --path.logs path/to/my/logs
+elastic-agent run -c myagentconfig.yml
+----
+
+++++
+<hr>
+++++
+
+[discrete]
+[[elastic-agent-uninstall-command]]
+== elastic-agent uninstall
+
+Permanently uninstall {agent} from the system.
+
+You must run this command as the root user (or Administrator on Windows)
+to remove files. 
+
+[discrete]
+=== Synopsis
+
+[source,shell]
+----
+elastic-agent uninstall [--force] [--help] [global-flags]
+----
+
+[discrete]
+=== Options
+
+`--force`::
+Uninstall {agent} and do not prompt for confirmation. This flag is helpful
+when using automation software or scripted deployments.
+
+`--help`::
+Show help for the `uninstall` command.
+
+{global-flags-link}
+
+[discrete]
+=== Examples
+
+[source,shell]
+----
+elastic-agent uninstall
+----
+
+++++
+<hr>
+++++
+
+[discrete]
+[[elastic-agent-upgrade-command]]
+== elastic-agent upgrade
+
+Upgrade the currently running {agent} to the specified version.
+
+[discrete]
+=== Synopsis
+
+[source,shell]
+----
+elastic-agent upgrade <version> [--source-uri <string>] [--help] [flags]
+----
+
+[discrete]
+=== Options
+
+`version`::
+The version of {agent} to upgrade to.
+
+`--source-uri <string>`::
+The source URI to download the new version from. By default, {agent} uses the
+Elastic Artifacts URL.
+
+`--help`::
+Show help for the `upgrade` command.
+
+{global-flags-link}
+
+[discrete]
+=== Examples
+
+[source,shell]
+----
+elastic-agent upgrade 7.10.1
 ----
 
 ++++