git-remote-helpers.txt: minor grammar fix

Signed-off-by: Max Horn <max@quendi.de>
Acked-by: Sverre Rabbelier <srabbelier@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-remote-helpers.txt

@@ -235,9 +235,9 @@ Commands are given by the caller on the helper's standard input, one per line.
 'capabilities'::
 	Lists the capabilities of the helper, one per line, ending
 	with a blank line. Each capability may be preceded with '*',
-	which marks them mandatory for git version using the remote
-	helper to understand (unknown mandatory capability is fatal
-	error).
+	which marks them mandatory for git versions using the remote
+	helper to understand. Any unknown mandatory capability is a
+	fatal error.
 
 'list'::
 	Lists the refs, one per line, in the format "<value> <name>