docs: few small changes (elastic#6926)

docs/legacy/sourcemaps.asciidoc

@@ -5,11 +5,12 @@
 <titleabbrev>Create and upload source maps (RUM)</titleabbrev>
 ++++
 
-IMPORTANT: {deprecation-notice-data}
-If you've already upgraded, please see <<source-map-how-to>> instead.
-
-NOTE: This guide is only for standalone APM Server users. Users running the <<apm-integration,APM integration>>
-need to use the Kibana {kibana-ref}/rum-sourcemap-api.html[source map upload API] instead.
+IMPORTANT: The APM Server source map endpoint has been deprecated in 7.16 and will be removed in 8.0.
+It is being replaced by the {kib} source map API.
+If you've already <<upgrade-to-apm-integration,upgraded to the Elastic APM integration>>,
+see the new <<source-map-how-to,{kib} source map upload guide>>.
++
+Standalone APM Server users will need to wait until 8.0 to use the new {kib} source map API.
 
 Minifying JavaScript bundles in production is a common practice;
 it can greatly improve the load time and network latency of your applications.

docs/source-map-how-to.asciidoc

@@ -34,8 +34,9 @@ Follow the steps below to enable source mapping your error stack traces in the A
 [[source-map-rum-initialize]]
 === Initialize the RUM Agent
 
-First, set the service name and version of your application when initializing the RUM Agent.
-The `serviceVersion` you choose might be the `version` from your `package.json`. For example:
+Set the service name and version of your application when initializing the RUM Agent.
+To make uploading subsequent source maps easier, the `serviceVersion` you choose might be the
+`version` from your `package.json`. For example:
 
 [source,js]
 ----
@@ -57,19 +58,18 @@ const serviceVersion = git.short()
 ----
 
 It can also be any other unique string that indicates a specific version of your application.
-APM Server uses the `serviceVersion` to match the correct source map file to each stack trace.
+The APM integration uses the service name and version to match the correct source map file to each stack trace.
 
 [float]
-[role="child_attributes"]
 [[source-map-rum-generate]]
 === Generate a source map
 
 To be compatible with Elastic APM, source maps must follow the
 https://sourcemaps.info/spec.html[source map revision 3 proposal spec].
 
 Source maps can be generated and configured in many different ways.
-For example, if you're using parcel, they are generated by default.
-If you are using webpack, some configuration may need to be done to generate a source map:
+For example, parcel automatically generates source maps by default.
+If you're using webpack, some configuration may be needed to generate a source map:
 
 [source,js]
 ----
@@ -138,7 +138,7 @@ curl -X POST "http://localhost:5601/api/apm/sourcemaps" \
 
 To ensure uploading source maps become a part of your deployment process,
 consider automating the process with a custom application.
-Here’s an example Node.js application that uploads the source map file created in the previous step:
+Here's an example Node.js application that uploads the source map file created in the previous step:
 
 [source,js]
 ----