Merge branch 'nd/tag-doc'

* nd/tag-doc:
  git-tag.txt: <commit> for --contains is optional
diff --git a/Documentation/git-tag.txt b/Documentation/git-tag.txt
index c418c44..404257d 100644
--- a/Documentation/git-tag.txt
+++ b/Documentation/git-tag.txt
@@ -103,8 +103,9 @@
 +
 This option is only applicable when listing tags without annotation lines.
 
---contains <commit>::
-	Only list tags which contain the specified commit.
+--contains [<commit>]::
+	Only list tags which contain the specified commit (HEAD if not
+	specified).
 
 --points-at <object>::
 	Only list tags of the given object.