docs: rename development-process/ to process/

As we'll type this a lot, after adding CodingStyle & friends,
let's rename the directory name to a shorter one.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

Documentation/index.rst

@@ -12,7 +12,7 @@ Contents:
    :maxdepth: 2
 
    kernel-documentation
-   development-process/index
+   process/index
    dev-tools/tools
    driver-api/index
    media/index