Update README.md (#3371)

Co-authored-by: yaphet <4414314+darionyaphet@users.noreply.github.com>

README.md

@@ -58,7 +58,7 @@ Please note that you need to install **Nebula Graph**, either by [installing sou
 ## Getting help
 In case you encounter any problems playing around **Nebula Graph**, please reach out for help:
 * [FAQ](https://docs.nebula-graph.io/2.0/2.quick-start/0.FAQ/)
-* [Forum](https://discuss.nebula-graph.io/)
+* [Discussions](https://github.com/vesoft-inc/nebula/discussions)
 
 ## Documentation