Merge branch 'sb/submodule-config-doc-drop-path' into maint

The "submodule.<name>.path" stored in .gitmodules is never copied
to .git/config and such a key in .git/config has no meaning, but
the documentation described it and submodule.<name>.url next to
each other as if both belong to .git/config.  This has been fixed.

* sb/submodule-config-doc-drop-path:
  documentation: improve submodule.<name>.{url, path} description

Documentation/config.txt

@@ -2805,12 +2805,13 @@ stash.showStat::
 	option will show diffstat of the stash.  Defaults to true.
 	See description of 'show' command in linkgit:git-stash[1].
 
-submodule.<name>.path::
 submodule.<name>.url::
-	The path within this project and URL for a submodule. These
-	variables are initially populated by 'git submodule init'. See
-	linkgit:git-submodule[1] and linkgit:gitmodules[5] for
-	details.
+	The URL for a submodule. This variable is copied from the .gitmodules
+	file to the git config via 'git submodule init'. The user can change
+	the configured URL before obtaining the submodule via 'git submodule
+	update'. After obtaining the submodule, the presence of this variable
+	is used as a sign whether the submodule is of interest to git commands.
+	See linkgit:git-submodule[1] and linkgit:gitmodules[5] for details.
 
 submodule.<name>.update::
 	The default update procedure for a submodule. This variable