Update CRD api docs only if sorted files different (googleforgames#1694)

Ordering of APIGroups do not change the logic of the resulted file contents
especially for the case when they are on the same level in the docs.
Commutative property of the enumeration.

site/gen-api-docs.sh

@@ -62,7 +62,7 @@ function sedeasy {
 }
 
 # do we have changes in generated API docs compared to previous version
-if ! diff $RESULT $OLD;
+if ! diff <(sort $RESULT) <(sort $OLD);
 then 
   echo "Output to a file $FILE"