Beats Doc Updates for 5.4

[dedemorton]

5.4

This list is a work-in-progress and doesn't accurately represent doc goals for 5.4 (yet)

• Resolve doc bugs and issues flagged for 5.4.0:
  • Move content about processors. See Move the content about processors #4058 (in progress, but not currently flagged for 5.4)
  • Fix the structure of the modules documentation. See Fix the structure of the Filebeat modules doc #4029
  • Clarify docs for Windows commands to indicate the Powershell is required. See Clarify doc for Windows commands to indicate that Powershell is required #3993
  • Document complex objects support in env/cli vars Document complex objects support in env/cli vars #3686
  • Document limitation of multiple host output interaction with LS when multiline is configured on the LS side Document limitation of multiple host output interaction with LS when multiline is configured on the LS side #4008
• Add more content about flows to the Packetbeat docs. Right now we only have config info here. What are flows? What kind of info can you get? When are they needed?
• Pull dev guide content into a single Beats Developer Guide Pull dev guide content into a single Beats Developer Guide #3738
• Update docs with info about official docker images.

Notes:

• Moved backlog to Beats doc updates for 5.6 #4193.
• Removed "Heartbeat rtt.us field is not documented" from this list because urso has an issue open for heartbeat ga to add more rtt measures.

[dedemorton]

Added #4197 to cover flows.