docs: improve discoverability of exclude pathspec

The ability to exclude paths with a negative pathspec is not mentioned
in the man pages for git grep and other commands where it might be
useful.

Add an example and a pointer to the pathspec glossary entry in the man
page for git grep to help the user to discover this ability.

Add similar pointers from the git-add and git-status man pages.

Additionally,

- Add a test for the behaviour when multiple exclusions are present.
- Add a test for the ^ alias.
- Improve name of existing test.
- Improve grammar in glossary description of the exclude pathspec.

Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Manav Rathi <mnvrth@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-add.txt

@@ -61,6 +61,9 @@ OPTIONS
 	the working tree.  Note that older versions of Git used
 	to ignore removed files; use `--no-all` option if you want
 	to add modified or new files but ignore removed	ones.
++
+For more details about the <pathspec> syntax, see the 'pathspec' entry
+in linkgit:gitglossary[7].
 
 -n::
 --dry-run::

Documentation/git-grep.txt

@@ -293,6 +293,9 @@ OPTIONS
 <pathspec>...::
 	If given, limit the search to paths matching at least one pattern.
 	Both leading paths match and glob(7) patterns are supported.
++
+For more details about the <pathspec> syntax, see the 'pathspec' entry
+in linkgit:gitglossary[7].
 
 Examples
 --------
@@ -309,6 +312,9 @@ Examples
 	Looks for a line that has `NODE` or `Unexpected` in
 	files that have lines that match both.
 
+`git grep solution -- :^Documentation`::
+	Looks for `solution`, excluding files in `Documentation`.
+
 GIT
 ---
 Part of the linkgit:git[1] suite

Documentation/git-status.txt

@@ -108,6 +108,8 @@ configuration variable documented in linkgit:git-config[1].
 	without options are equivalent to 'always' and 'never'
 	respectively.
 
+<pathspec>...::
+	See the 'pathspec' entry in linkgit:gitglossary[7].
 
 OUTPUT
 ------

Documentation/glossary-content.txt

@@ -407,7 +407,7 @@ these forms:
 
 exclude;;
 	After a path matches any non-exclude pathspec, it will be run
-	through all exclude pathspec (magic signature: `!` or its
+	through all exclude pathspecs (magic signature: `!` or its
 	synonym `^`). If it matches, the path is ignored.  When there
 	is no non-exclude pathspec, the exclusion is applied to the
 	result set as if invoked without any pathspec.

t/t6132-pathspec-exclude.sh

@@ -25,7 +25,7 @@ EOF
 	test_cmp expect actual
 '
 
-test_expect_success 'exclude only no longer errors out' '
+test_expect_success 'exclude only pathspec uses default implicit pathspec' '
 	git log --oneline --format=%s -- . ":(exclude)sub" >expect &&
 	git log --oneline --format=%s -- ":(exclude)sub" >actual &&
 	test_cmp expect actual
@@ -183,4 +183,15 @@ EOF
 	test_cmp expect actual
 '
 
+test_expect_success 'multiple exclusions' '
+	git ls-files -- ":^*/file2" ":^sub2" >actual &&
+	cat <<-\EOF >expect &&
+	file
+	sub/file
+	sub/sub/file
+	sub/sub/sub/file
+	EOF
+	test_cmp expect actual
+'
+
 test_done