Add 0.8 compatibility note

Author: webmaster128

README.md

@@ -12,8 +12,9 @@ are compatible with a Cosmos SDK based runtime, [`wasmd`](https://github.com/Cos
 
 Compatibility:
 
+* Contracts built with CosmWasm `v0.8.x` (unreleased) will run on `wasmd` `v0.8.x` (unreleased) (master branch)
+* Contracts built with CosmWasm `v0.7.x` will run on `wasmd` `v0.7.x` (0.7 branch)
 * Contracts built with CosmWasm `v0.6.3+` will run on `wasmd` `v0.6.x`
-* Contracts built with CosmWasm `v0.7.x` will run on `wasmd` `v0.7.x`
 
 ## Overview