chore: update readme Developing instructions (#2623)

packages/cli/README.md

@@ -82,15 +82,14 @@ This project is built with [lerna](https://lerna.js.org/). The core plugins are
 
 After cloning the repo
 1. Run `yarn` to install dependencies
-2. Run `yarn lerna bootstrap` set up Lerna and link the packages together
-    - This repo currently uses an older version of Lerna. We recommend using the version specified in the package.json instead of a newer version that you may have installed globally.
+2. Run `yarn build` to build the CLI. This will need to be re-run any time you make changes and want to test them locally.
 
 To execute Heroku CLI commands locally, use `./bin/run <command>`. For example, to run the `heroku apps` command with your local code, run `./bin/run apps` from the root directory.
 
 Testing
 =======
 
-Run all tests with `yarn lerna run test`.
+Run all tests with `yarn test`.
 
 Run one test, in this case plugin-certs-v5, with `yarn lerna run --scope @heroku-cli/plugin-certs-v5 test`.