Add Proxy-Wasm update to 3/26 agenda. (#249)

Author: PiotrSikora

meetings/2020/WASI-03-26.md

@@ -47,5 +47,6 @@ Installation is required, see the calendar invite.
        1. `-lwasi-emulated-raise`
        1. ...
        1. `-lwasi-emulated-all` ?
+    1. [Proxy-Wasm](https://github.com/proxy-wasm) update.
 
 ## Meeting Notes