chore: added links, clarified order of steps

CONTRIBUTING.md

@@ -3,7 +3,8 @@
 Each proposal to Mainnet (agoric-3) should be contributed to this repo before being proposed to the chain.
 
 1. Prepare the proposal and verify it by creating a proposal in
-   agoric-sdk/a3p-integration. See the README there for more details
+   agoric-sdk/a3p-integration. See the
+   [README](https://github.com/Agoric/agoric-sdk/blob/master/a3p-integration/README.md) for more details
 
 2. Submit a PR to this repo in which the proposal has a _pending_ name (e.g. `a:my-contract`)
 
@@ -14,6 +15,8 @@ Each proposal to Mainnet (agoric-3) should be contributed to this repo before be
 5. When the proposal passes, submit a PR here converting the pending proposal to a passed one (by
    changing the letter to the submission number)
 
-6. Remove the proposal from a3p-integration. Move generally useful tools to synthetic-chain
-   here. Move tests that should continue to pass afterwards into a3p-integration/z:acceptance
+6. clean up a3p-integration
+  a. Move generally useful tools to the `@agoric/synthetic-chain` package.
+  b. Move tests that should continue to pass afterwards into a3p-integration/z:acceptance
+  c. Remove the proposal from a3p-integration.