clone: fixup recurse_submodules option

The recurse_submodules option was added in ccdd3da6 to bring 'git clone'
into line with 'git fetch' and future commands. The correct option should
have been "recurse-submodules".

Signed-off-by: Chris Packham <judge.packham@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/builtin/clone.c b/builtin/clone.c
index 61e0989..82a6938 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -66,7 +66,7 @@
 		    "setup as shared repository"),
 	OPT_BOOLEAN(0, "recursive", &option_recursive,
 		    "initialize submodules in the clone"),
-	OPT_BOOLEAN(0, "recurse_submodules", &option_recursive,
+	OPT_BOOLEAN(0, "recurse-submodules", &option_recursive,
 		    "initialize submodules in the clone"),
 	OPT_STRING(0, "template", &option_template, "path",
 		   "path the template repository"),