Update docs for Drupal 7

[sobi3ch]

On http://jdrupal.easystreet3.com/7/docs/Install page (point 2 2. Enable the Services Module and Create Endpoint) #you should add point like:

Enable rest_server module

..otherwise there is no chance to pick up server from and save it on the end.

[signalpoint]

@sobi3ch Thank you for pointing this out, I've added a note to the docs: https://github.com/easystreet3/jDrupal/commit/ab723661ca29464eede50d5ab34a969676ca99cd