Updated readme with contribution section. More help welcome 😃

Author: boukeversteegh

README.md

@@ -302,6 +302,32 @@ datetime.datetime(2019, 1, 1, 11, 59, 58, 800000, tzinfo=datetime.timezone.utc)
 {'ts': '2019-01-01T12:00:00Z', 'duration': '1.200s'}
 ```
 
+
+## Contribution
+
+
+Join us on [Slack](https://join.slack.com/t/betterproto/shared_invite/zt-f0n0uolx-iN8gBNrkPxtKHTLpG3o1OQ)!
+
+There's lots to do, and we're working hard, so any help is welcome!
+
+What can you do?
+
+- :+1: Vote on [issues](https://github.com/danielgtaylor/python-betterproto/issues).
+- :speech_balloon: Give feedback on [Pull Requests](https://github.com/danielgtaylor/python-betterproto/pulls) and [Issues](https://github.com/danielgtaylor/python-betterproto/issues):
+    - Suggestions
+    - Express approval
+    - Raise concerns
+- :small_red_triangle: Create an issue:
+    - File a bug (please check its not a duplicate)
+    - Propose an enhancement
+- :white_check_mark: Create a PR:
+    - Creating a failing test-case to make bug-fixing easier
+    - Fix any of the open issues
+        - [Good first issues](https://github.com/danielgtaylor/python-betterproto/issues?q=is%3Aissue+is%3Aopen+label%3A%22good+first+issue%22)
+        - [Issues with tests](https://github.com/danielgtaylor/python-betterproto/issues?q=is%3Aissue+is%3Aopen+label%3A%22has+test%22)
+    - New bugfix or idea
+        - If you'd like to discuss your idea first, join us on Slack!
+
 ## Development
 
 Join us on [Slack](https://join.slack.com/t/betterproto/shared_invite/zt-f0n0uolx-iN8gBNrkPxtKHTLpG3o1OQ)!
@@ -434,10 +460,10 @@ protoc \
   - [x] Enum strings
   - [x] Well known types support (timestamp, duration, wrappers)
   - [x] Support different casing (orig vs. camel vs. others?)
-- [ ] Async service stubs
+- [x] Async service stubs
   - [x] Unary-unary
   - [x] Server streaming response
-  - [ ] Client streaming request
+  - [x] Client streaming request
 - [x] Renaming messages and fields to conform to Python name standards
 - [x] Renaming clashes with language keywords
 - [x] Python package