Documentation/process/applying-patches: Activate linux-next man hyperlink

Documentation/process/applying-patches: Activate linux-next man hyperlink

There is a url for linux-next in the 'applying-patches.rst', but it's
surrounded by backquotes.  So the url doesn't have a hyperlink in the
built document.  To let readers easily move to the page, this commit
puts the url outside of the backquotes so that a hyperlink to the url
can be automatically made.

Signed-off-by: SeongJae Park <sjpark@amazon.de>
Link: https://lore.kernel.org/r/20210812095030.4704-1-sj38.park@gmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>