Document pacman hook that symlinks old kernel modules

Fixes #24.

man8/snap-pac.8

@@ -228,6 +228,21 @@ something like the following:
 
 .EE
 
+.SS How do I link old kernel modules?
+This behavior is no longer a part of this package. Use a pacman hook like the following:
+
+    [Trigger]
+    Operation = Upgrade
+    Operation = Install
+    Operation = Remove
+    Type = Package
+    Target = linux
+
+    [Action]
+    Description = Symlinking old kernel modules...
+    When = PostTransaction
+    Exec = /usr/bin/bash -c "find /usr/lib/modules -xtype l -delete; ln -sv /.snapshots/$(snapper -c root list | awk 'END{print $1}')/snapshot/usr/lib/modules/$(uname -r) /usr/lib/modules/"
+
 .SH HOMEPAGE
 https://github.com/wesbarnett/snap-pac