MIGRATING.md update

Author: uint

MIGRATING.md

@@ -7,9 +7,8 @@ major releases of `cosmwasm`. Note that you can also view the
 ## 1.0.0 -> 1.1.0
 
 - There are changes to how we generate schemas, resulting in less boilerplace
-  maintenance for smart contract devs. The changes are backwards-compatible -
-  old contracts will continue working for a while, but it's highly recommended
-  to migrate now.
+  maintenance for smart contract devs. Old contracts will continue working for a
+  while, but it's highly recommended to migrate now.
 
   Your contract should have a `cosmwasm_schema` dependency in its `Cargo.toml`
   file. Move it from `dev-dependencies`to regular `dependencies`.
@@ -86,6 +85,10 @@ major releases of `cosmwasm`. Note that you can also view the
   }
   ```
 
+This changes the format of the schemas generated by the contract. They're now in
+one structured, unified file (parseable by machines) rather than a bunch of
+arbitrary ones.
+
 ## 1.0.0-beta -> 1.0.0
 
 - The minimum Rust supported version is 1.56.1. Verify your Rust version is >=