Fix broken link in Documentation/process/kernel-docs.rst

Kernel Glossary has moved from /Glossary to /KernelGlossary
on kernelnewbies.org. This patch corrects this link.

Signed-off-by: Grigory Shipunov <mail@oxapentane.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>