* Preliminary changes
* More changes
* Updating Logs app content.
* Few final tweaks after reading through
* Review comments, adding a redirect for a removed bookmark, just in case.
This PR adds documentation about the new log column feature. To keep the docs Logs UI readable as new features are added, they are now restructured into four pages:
* a landing page with a full screenshot linking to the subsequent section
* a "getting started" page to link to the tutorials on ingesting log data
* a "using" page to explain the main features of the Logs UI
* a "configuring" page to explain the configuration UI
closeselastic/kibana#36025
