message: update cardhost README
diff: # cardhost
  -The cardhost is an application container that hosts cards. The cardhost is deployed as a stand-alone ember application outside of the mono repo. Because the cardhost is deployed as an isolated module outside of the mono repo, ***if any of its mono repo peer modules change, you'll need to rev the mono repo in order for the deployed cardhost to pick up the changes.***
  +The cardhost, aka Card Builder, is an application container that hosts cards. The cardhost is deployed as a stand-alone ember application outside of the mono repo.
  +It works together with the Hub.
  ## Prerequisites
  @@ -23,25 +24,47 @@ You will need the following things properly installed on your computer.
  ## Running / Development
  * `yarn start-prereqs`
  -* `INDEX_INTERVAL=120 yarn start-hub`
  +* `yarn start-hub`
  * In a new tab, `yarn start-ember`
  -
  +* Alternately, start both the back and front end with `yarn start`
  * Visit your app at [http://localhost:4200](http://localhost:4200).
  * Visit your tests at [http://localhost:4200/tests](http://localhost:4200/tests).
  -`INDEX_INTERVAL` determines how often the hub should reindex data, in minutes.
  -It is recommended to set this number high for local development.
  +The cardhost app can only function if it is run together with the back end.
  +Both local development and the test suite rely on having access to the full stack.
  +
  +### Common server configuration
  +
  +#### `DEV_DIR`
  +
  +If you would like your cards to be saved to a git repository on your hard drive, specify the path to an existing, separate git repository when you start the servers.
  +Add `cards` to the end of the path, since that's where cards will be saved.
  -### Code Generators
  +```sh
  +yarn stop-prereqs # clear realms and ephemeral cards
  +DEV_DIR="path/to/your/git/repo/cards" yarn start
  +```
  -Make use of the many generators for code, try `ember help generate` for more details
  +#### `HUB_URL`
  +
  +Use a back end other than the default of `localhost:3000`:
  +
  +```sh
  +HUB_URL=http://localhost:8080 npx ember serve
  +```
  ### Running Tests
  * `yarn start-prereqs`
  +* `yarn test` to run all tests, including linters
  * `ember test`
  -* `ember test --server`
  +* `ember test --server` to run tests continuously
  +* `ember test --filter "some-test-name"` to run specific tests
  +
  +### Writing tests
  +
  +See CONTRIBUTING.md
  ### Linting
  @@ -58,7 +81,7 @@ From the root of the repository:
  ### Deploying
  -Deploying is done from `master` automatically via CI/CD.
  +Deploying is done from `master` automatically via CI/CD with GitHub Actions.
  ## Further Reading / Useful Links
  