doc txt & -h consistency: word-wrap

Change the documentation and -h output for those built-in commands
where both the -h output and *.txt were lacking in word-wrapping.

There are many more built-ins that could use this treatment, this
change is narrowed to those where this whitespace change is needed to
make the -h and *.txt consistent in the end.

In the case of "Documentation/git-hash-object.txt" and
"builtin/hash-object.c" this is not a "doc txt & -h consistency"
change, as we're changing both versions, doing so here makes a
subsequent change smaller.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/diagnose.c

@@ -3,7 +3,8 @@
 #include "diagnose.h"
 
 static const char * const diagnose_usage[] = {
-	N_("git diagnose [-o|--output-directory <path>] [-s|--suffix <format>] [--mode=<mode>]"),
+	N_("git diagnose [-o|--output-directory <path>] [-s|--suffix <format>]\n"
+	   "             [--mode=<mode>]"),
 	NULL
 };