Mention Redis version

Author: defunkt

README.markdown

@@ -485,6 +485,8 @@ tool that's best for your app.
 Installing Redis
 ----------------
 
+Resque requires Redis 0.900 or higher.
+
 Resque uses Redis' lists for its queues. It also stores worker state
 data in Redis.
 
@@ -529,6 +531,9 @@ Resque Dependencies
 If you cannot install `yajl-ruby` (JRuby?), you can install the `json`
 gem and Resque will use it instead.
 
+When problems arise, make sure you have the newest versions of the
+`redis` and `redis-namespace` gems.
+
 
 Installing Resque
 -----------------