Docs/process/index: Remove riscv/patch-acceptance from 'Other material' section

'patch-acceptance' on 'Other material' section of 'process/index', which
is for unsorted documents, is actually well organized under
'arch/riscv/' directory, and linked on the index document of the
directory.  Remove it from the 'Other material' section.
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20240624185312.94537-3-sj@kernel.org

Documentation/process/index.rst

@@ -115,7 +115,6 @@ lack of a better place.
 
    magic-number
    clang-format
-   ../arch/riscv/patch-acceptance
 
 .. only::  subproject and html