Retire patch porting documentation

The ZoL repository was converted in to the official OpenZFS
repository which works on both FreeBSD and Linux.  There's
no longer a need to document the process of cherry-picking
changes from Illumos in to the ZoL repository.

Signed-off-by: Brian Behlendorf <[email protected]>

Author: behlendorf

docs/Developer Resources/OpenZFS Patches.rst

@@ -8,6 +8,5 @@ Developer Resources
 
    Custom Packages
    Building ZFS
-   OpenZFS Patches
    OpenZFS Documentation <https://openzfs.org/wiki/Developer_resources>
    Git and GitHub for beginners