Cleanup subcommand documentation for git-remote.

Jakub Narebski pointed out the positional notation in git-remote's
documentation was very confusing, especially now that we have 3
supported subcommands.  Instead of referring to subcommands by
position, refer to them by name.

Signed-off-by: Shawn O. Pearce <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Documentation/git-remote.txt

@@ -19,18 +19,33 @@ DESCRIPTION
 
 Manage the set of repositories ("remotes") whose branches you track.
 
-With no arguments, shows a list of existing remotes.
 
-In the second form, adds a remote named <name> for the repository at
+COMMANDS
+--------
+
+With no arguments, shows a list of existing remotes.  Several
+subcommands are available to perform operations on the remotes.
+
+'add'::
+
+Adds a remote named <name> for the repository at
 <url>.  The command `git fetch <name>` can then be used to create and
 update remote-tracking branches <name>/<branch>.
 
-In the third form, gives some information about the remote <name>.
+'show'::
 
-In the fourth form, deletes all stale tracking branches under <name>.
+Gives some information about the remote <name>.
+
+'prune'::
+
+Deletes all stale tracking branches under <name>.
 These stale branches have already been removed from the remote repository
 referenced by <name>, but are still locally available in "remotes/<name>".
 
+
+DISCUSSION
+----------
+
 The remote configuration is achieved using the `remote.origin.url` and
 `remote.origin.fetch` configuration variables.  (See
 gitlink:git-config[1]).