add get in touch to README

Author: nf-s

README.md

@@ -8,6 +8,11 @@ This is a complete website built using the TerriaJS library. See the [TerriaJS R
 
 For instructions on how to deploy your map, see [the documentation here](doc/deploying/deploying-to-aws.md).
 
+To get in touch:
+
+- Join the [TerriaJS Github Discussion](https://github.com/TerriaJS/terriajs/discussions)
+- Raise issues in the [TerriaJS Github issue tracker](https://github.com/TerriaJS/terriajs/issues/new)
+
 ---
 
 ### We have released TerriaJS v8.3.0 (2023-05-22)