message: Add documentation about how to run lint and fix dependencies
diff: @@ -185,6 +185,29 @@ Ensure you've followed the above development instructions and then:
  yarn test
  ```
  +### Running lint
  +
  +To check your code complies with the project style, ensure you've followed the
  +above development instructions and then:
  +
  +```bash
  +yarn lint
  +```
  +
  +### Dependency problems
  +
  +If you see errors (particularly "Cannot find module") running the lint or test
  +commands, and `yarn install` doesn't fix them, it may be because
  +yarn is not fetching git dependencies eagerly enough.
  +
  +Try running this:
  +
  +```bash
  +yarn cache clean && yarn install --force
  +```
  +
  +Now the yarn commands should work as normal.
  +
  ### End-to-End tests
  Make sure you've got your Element development server running (by doing `yarn
  