Correct GET operation for services in README.md
Correct GET operation for services in README.md

According to https://github.com/mgonto/restangular/blob/3ff1bcc5dc723e3e19b06e800e8949f69a4357ea/src/restangular.js#L1247 only 3 operations (`one`, `post` and `getList`) are allowed. Using `get(:id)` does not work.
mgonto/restangular,mrahhal/restangular