Patch that modifies git usage message

[Alangi Derick]

This patch just modifies the "usage" word to "Usage" which enhances
readability. Below is the patch

Regards
Alangi Derick Ndimnain

diff --git a/git.c b/git.c
index 42a4ee5..481aa74 100644
--- a/git.c
+++ b/git.c
@@ -667,7 +667,7 @@ int main(int argc, char **av)
 	} else {
 		/* The user didn't specify a command; give them help */
 		commit_pager_choice();
-		printf("usage: %s\n\n", git_usage_string);
+		printf("Usage: %s\n\n", git_usage_string);
 		list_common_cmds_help();
 		printf("\n%s\n", _(git_more_info_string));
 		exit(1);