[PATCH] c-user: Use new template for feature config opts

[Sebastian Huber]

On 18/03/2020 16:52, Sebastian Huber wrote:

> Try to bring all descriptions up to date.  Add cross-references to
> several options.
>
> Update #3900.

I checked in a slightly updated patch. I added a new option type 
"feature-enable" to produce a standard text for the default configuration:

https://git.rtems.org/sebh/rtems-qual.git/commit/?id=f85bb0bbaece4c3be58d3b023fd4d118e2c59030

A good example for the new template is here:

https://docs.rtems.org/branches/master/c-user/config/event-record.html

I will work now on an update of the integer type configuration options:

https://devel.rtems.org/ticket/3901