Documentation/features: Allow comments in arch features files

The list-arch.sh script considers lines beginning with "#" as match for
the feature table.

Given that those tables are never in lines beginning with "#",
add a reverse grep on "^#" when matching the "ok/TODO" state of
the architecture.

This allows adding comments within the feature files, for instance
describing the architecture requirements for the feature in each
architecture.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-doc@vger.kernel.org
Link: http://lkml.kernel.org/r/1518282058-24226-1-git-send-email-mathieu.desnoyers@efficios.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>