[LTP] [PATCH v2] macros: Add basic docs

[Petr Vorel]

Hi Cyril,

> Describe all "public" macros.
> Move variables to the top.
> Add header to the sphinx doc.

> Signed-off-by: Petr Vorel <pvorel@suse.cz>
> Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
> ---
> I've took the changes from Peter and:

> - added more verbose description that would hopefully explain the macros
>   better

> - added documentation for a few macros that was missing previously

> - moved the macros into its own menu category since the Core LTP API is
>   long enough already

Thanks a lot for greatly improving and finishing the work. This will help not
only to the newcomers to understand the test code.

Kind regards,
Petr