Merge branch 'review-revamp-issues-docs' into 'master'

Refactor Issues doc

Closes #56877

See merge request gitlab-org/gitlab-ce!24695

doc/user/project/issues/issues_functionalities.md

-# GitLab Issues Functionalities
+# Issue Data and Actions
 
 Please read through the [GitLab Issue Documentation](index.md) for an overview on GitLab Issues.
 
-## Issues Functionalities
+## Parts of an Issue
 
 The image below illustrates what an issue looks like: