doc: Update rST to not reference the old wiki

In two places we had references to the old wiki pages instead of links
to the relevant part of our documentation. Update (and slightly reword)
these spots.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/doc/develop/process.rst b/doc/develop/process.rst
index 0542b3f..0c6fb31 100644
--- a/doc/develop/process.rst
+++ b/doc/develop/process.rst
@@ -23,9 +23,8 @@
 Phases of the Development Process
 ---------------------------------
 
-U-Boot development takes place in `Release Cycles
-<https://www.denx.de/wiki/U-Boot/ReleaseCycle>`_.  A Release Cycle lasts
-normally for three months.
+U-Boot development takes place in a :doc:`release_cycle`. A Release Cycle
+lasts normally for three months.
 
 The first three weeks of each Release Cycle are called *Merge Window*.
 
diff --git a/doc/develop/version.rst b/doc/develop/version.rst
index 5c9046a..de11836 100644
--- a/doc/develop/version.rst
+++ b/doc/develop/version.rst
@@ -9,7 +9,7 @@
 weeks as the project heads to the next release. So 2020.10-rc1 was the first
 release candidate (RC), tagged soon after 2020.07 was released.
 
-See https://www.denx.de/wiki/view/U-Boot/ReleaseCycle for full details.
+See :doc:`release_cycle` for full details.
 
 Within the build system, various Makefile variables are created, making use of
 VERSION, PATCHLEVEL and EXTRAVERSION defined at the top of 'Makefile'. There is