Improve documentation of engine loading
Improve documentation of engine loading

Change-Id: I4b9ffb42185d203984968559826f9327072f9f07
Reviewed-on: http://review.couchbase.org/66443
Tested-by: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Daniel Owen <b3fc0e1a51f252986e60be7da121b74d3ac6845f@couchbase.com>
Reviewed-by: Dave Rigby <a09264da4832c7ff1d3bf1608a19f4b870f93750@couchbase.com>
Reviewed-by: Jim Walker <1cd02e31b43620d7c664e038ca42a060d61727b9@couchbase.com>

daverigby/memcached,daverigby/kv_engine,daverigby/kv_engine,couchbase/memcached,couchbase/memcached,daverigby/memcached,couchbase/memcached,daverigby/memcached,daverigby/kv_engine,daverigby/memcached,daverigby/kv_engine,couchbase/memcached