Backport of Updated docs added explanation. into release/1.15.x (#17792)

* backport of commit 2f94024b35

* backport of commit 7626d0992d

* backport of commit 79aabc958a

* backport of commit 44eee4168b

* fix conflicts

* Updated docs added explanation. (#17751)

* init

* fix tests

* added -detailed in docs

* added change log

* fix doc

* checking for entry in map

* fix tests

* removed detailed flag

* removed detailed flag

* revert unwanted changes

* removed unwanted changes

* updated change log

* pr review comment changes

* pr comment changes single API instead of two

* fix change log

* fix tests

* fix tests

* fix test operator raft endpoint test

* Update .changelog/17582.txt

Co-authored-by: Semir Patel <semir.patel@hashicorp.com>

* nits

* updated docs

* explanation added

---------

Co-authored-by: Semir Patel <semir.patel@hashicorp.com>

---------

Co-authored-by: Ashesh Vidyut <ashesh.vidyut@hashicorp.com>
Co-authored-by: Ashesh Vidyut <134911583+absolutelightning@users.noreply.github.com>
Co-authored-by: Semir Patel <semir.patel@hashicorp.com>

website/content/commands/operator/raft.mdx

@@ -66,6 +66,10 @@ Raft configuration.
 `Voter` is "true" or "false", indicating if the server has a vote in the Raft
 configuration.
 
+`Commit Index` is the last log index the server has a record of in its Raft log.
+
+`Trails Leader By` is the difference in commit index the server has from the leader.
+
 #### Command Options
 
 - `-stale` - Enables non-leader servers to provide cluster state information.