Documentation: process: replace outdated LTS table w/ link

The existing table was a bit outdated.

3.16 was EOL in 2020.
4.4 was EOL in 2022.

5.10 is new in 2020.
5.15 is new in 2021.

We'll see if 6.1 becomes LTS in 2022.

Rather than keep this table updated, it does duplicate information from
multiple kernel.org pages. Make one less duplication site that needs to
be updated and simply refer to the kernel.org page on releases.

Suggested-by: Tyler Hicks <[e-mail]>
Suggested-by: Bagas Sanjaya <[e-mail]>
Signed-off-by: Nick Desaulniers <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>
Link: https://lore.kernel.org/stable/20221014171040.849726-1-ndesaulniers%40google.com
Reviewed-by: Tyler Hicks (Microsoft) <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Corbet <[e-mail]>

Documentation/process/2.Process.rst

···
 5.2.21 was the final stable update of the 5.2 release.
 
 Some kernels are designated "long term" kernels; they will receive support
-for a longer period.  As of this writing, the current long term kernels
-and their maintainers are:
+for a longer period.  Please refer to the following link for the list of active
+long term kernel versions and their maintainers:
 
-	======  ================================	=======================
-	3.16	Ben Hutchings				(very long-term kernel)
-	4.4	Greg Kroah-Hartman & Sasha Levin	(very long-term kernel)
-	4.9	Greg Kroah-Hartman & Sasha Levin
-	4.14	Greg Kroah-Hartman & Sasha Levin
-	4.19	Greg Kroah-Hartman & Sasha Levin
-	5.4	Greg Kroah-Hartman & Sasha Levin
-	======  ================================	=======================
+	https://www.kernel.org/category/releases.html
 
 The selection of a kernel for long-term support is purely a matter of a
 maintainer having the need and the time to maintain that release.  There