[PATCH 05 of 10 RFC v2] help: document compat mode

[Jun Wu]

Excerpts from David Soria Parra's message of 2017-03-12 15:40:28 -0700:

[...]

> +``compat``
> +    String: Compatibility mode for the ui. Possible values are compat

Maybe also quote "compat" and "latest" in these 2 lines.

> +    or latest (default: compat). ``compat`` provides backwards compatible
> +    ui behavior. ``latest`` enables additional config settings aiming to
> +    improve user experience. (see ``HGPLAIN`` for compatibility modes in
> +    non-interactive environments)
> +
>  ``debug``
>      Print debugging information. (default: False)
>  

It seems that we may want a "hg help compat" to document the exact
differences.