Update documentation (#176)

Author: alexkeating

README.md

@@ -73,7 +73,7 @@ This contract can be thought of as governance's "admin" on the spoke, with impor
   3. Multi gov will need to be redeployed for the new governor.
 - `HubVotePool`: A new contract must be deployed that reads the state from the old `HubVotePool` vote state at a given timestamp and then all of the spoke vote aggregators must be registered on the new hub vote pool.
 - `SpokeVoteAggregator`: A new spoke vote aggregator will need to be deployed which must be able to read the vote totals for any active proposals at the timestamp of the new deploy. The new spoke vote aggregator must be registered on the `HubVotePool`.
-- `SpokeMessageExecutor`: This contract can be upgraded via a UUPS proxy via the airlock.
+- `SpokeMessageExecutor`: This implementation is deployed using the UUPS proxy pattern and can be upgraded by successful governance proposals that call back into this contract from the spoke airlock.
 
 ### Diagram