[PATCH] gdb/thread: fine-tune 'info threads' help text

[Philippe Waroquiers]

On Mon, 2020-10-19 at 15:57 +0000, Aktemur, Tankut Baris via Gdb-patches wrote:
> > I would put a blank line just after the "Usage:", because I like when things are well
> > visually separated.  But it LGTM regardless.
> 
> I agree, but I checked some other arbitrary commands manually, and also did a
> `grep -A 1 "Usage:" *.c`, and found that a great portion of commands do not print that
> separator newline.  For consistency, let me push without the newline. 

Some conventions/invariants regarding the command help text
are verified by command-def-selftests.c

If we want to have consistently a blank line (or consistently no blank line)
before  Usage:, then that is an additional verification we can put in check_doc.

Philippe