doc: stash: synchronize <pathspec> description

This patch continues the effort that is already applied to
`git commit`, `git reset`, `git checkout` etc.

1) Added reference to 'linkgit:gitglossary[7]'.
2) Fixed mentions of incorrectly plural "pathspecs".

Signed-off-by: Alexandr Miloslavskiy <alexandr.miloslavskiy@syntevo.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-stash.txt

@@ -56,13 +56,13 @@ push [-p|--patch] [-k|--[no-]keep-index] [-u|--include-untracked] [-a|--all] [-q
 For quickly making a snapshot, you can omit "push".  In this mode,
 non-option arguments are not allowed to prevent a misspelled
 subcommand from making an unwanted stash entry.  The two exceptions to this
-are `stash -p` which acts as alias for `stash push -p` and pathspecs,
+are `stash -p` which acts as alias for `stash push -p` and pathspec elements,
 which are allowed after a double hyphen `--` for disambiguation.
 
 save [-p|--patch] [-k|--[no-]keep-index] [-u|--include-untracked] [-a|--all] [-q|--quiet] [<message>]::
 
 	This option is deprecated in favour of 'git stash push'.  It
-	differs from "stash push" in that it cannot take pathspecs.
+	differs from "stash push" in that it cannot take pathspec.
 	Instead, all non-option arguments are concatenated to form the stash
 	message.
 
@@ -213,6 +213,8 @@ The new stash entry records the modified states only for the files
 that match the pathspec.  The index entries and working tree files
 are then rolled back to the state in HEAD only for these files,
 too, leaving files that do not match the pathspec intact.
++
+For more details, see the 'pathspec' entry in linkgit:gitglossary[7].
 
 <stash>::
 	This option is only valid for `apply`, `branch`, `drop`, `pop`,