docs: Remove remaining references to metag

Remove any remaining references to the Meta architecture in
Documentation/, primarily from Documentation/features/.

Signed-off-by: James Hogan <jhogan@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-metag@vger.kernel.org
Cc: linux-doc@vger.kernel.org

Documentation/features/time/context-tracking/arch-support.txt

@@ -19,7 +19,6 @@
     |        ia64: | TODO |
     |        m32r: | TODO |
     |        m68k: | TODO |
-    |       metag: | TODO |
     |  microblaze: | TODO |
     |        mips: |  ok  |
     |     mn10300: | TODO |