Documentation/git-commit-tree: remove description of a nonexistent limitation

Noticed by Geoff Richards.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-commit-tree.txt

@@ -72,7 +72,7 @@ GIT_AUTHOR_EMAIL:
 		name = "Your Name"
 		email = "your@email.address.xz"
 
-A commit comment is read from stdin (max 999 chars). If a changelog
+A commit comment is read from stdin. If a changelog
 entry is not provided via "<" redirection, "git-commit-tree" will just wait
 for one to be entered and terminated with ^D.