Docs/process/index: Remove unaligned-memory-access from 'Other material'

Docs/process/index: Remove unaligned-memory-access from 'Other material'

'unaligned-memory-access document' is linked on 'Other material' section
of 'core-api/index', which is for unsorted documents.  But it is
actually well organized under 'core-api/' directory, and linked on the
'core-api/index'.  Remove it from 'Other material' section of
'process/index' document.

Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20240624185312.94537-2-sj@kernel.org