[docs] Update readme
[docs] Update readme

* added link to Flink Forward presentation
niklasteichmann/gradoop,galpha/gradoop,s1ck/gradoop,rostam/gradoop,smee/gradoop,rostam/gradoop,smee/gradoop,galpha/gradoop,dbs-leipzig/gradoop,dbs-leipzig/gradoop,niklasteichmann/gradoop,s1ck/gradoop