docs: how to add an upgrade layer

packages/deployment/upgrade-test/Readme.md

@@ -102,6 +102,21 @@ docker exec -it sweet_edison bash
 To make the wallet ui talk to your local chain, set the network config to
 `https://local.agoric.net/network-config`
 
+## To add an upgrade
+
+1. Update the upgrade handler in app.go
+2. Duplicate the last pair of UPGRADE and TEST blocks
+3. Update their number from the UPGRADE / DEST block at the end
+4. Make directory for tests (e.g. `agoric-upgrade-12`)
+4. Make directory for ugprade (e.g. `agoric-upgrade-11-to-12` with a `.keep`)
+5. Update the UPGRADE/DEST pair to be your new upgrade (THIS_NAME matching the upgrade handler string in app.go)
+6. Update the `Makefile`
+  - the two targets to `Makefile` (e.g. `agoric-upgrade-11-to-12` and `agoric-upgrade-12`)
+  - set the default TARGET (e.g. `agoric-upgrade-12`)
+  - add the DEST target to the `.phony` in `Makefile`
+7. Test with `make local_sdk build run`
+
+
 ## Development
 
 You can iterate on a particular upgrade by targeting. When you exit and run again, it will be a fresh state.