Add poll for unshared atomics semantics

The proposed semantics can be found in WebAssembly/threads#147

Author: tlively

2020/CG-01-21.md

@@ -25,6 +25,7 @@ Installation is required, see the calendar invite.
 1. Adoption of the agenda
 1. Proposals and discussions
     1. Review of action items from prior meeting.
+    1. Poll for approval of the proposed semantics for atomic operations on unshared memory (https://github.com/WebAssembly/threads/pull/147)
 1. Closure
 
 ## Agenda items for future meetings