docs: replace yarn with npm (#352)

CONTRIBUTING.md

@@ -10,22 +10,21 @@ commit messaging follow the format
 ### Build Requirements
 To set up your work environment you'll need to use
  * [NodeJS](https://nodejs.org/)
- * [Yarn](https://yarnpkg.com)
  * And if you plan on making container contributions you may want to setup
     - [Docker](https://docs.docker.com/engine/installation/) or
     - [Podman](https://github.com/containers/podman), Homebrew can be used for the install `$ brew install podman`, [Easy setup directions here](https://marcusnoble.co.uk/2021-09-01-migrating-from-docker-to-podman/)
 
 ### Developing
 To start work
   ```shell
-  $ yarn
-  $ yarn start:dev
+  $ npm install
+  $ npm run start:dev
   ```
 
 #### Testing during development
 Jest is used for the unit test framework. To run unit tests during development open a terminal instance and run
   ```shell
-  $ yarn test:dev
+  $ npm run test:dev
   ```
 
 This should also let you update the code snapshots.
@@ -39,11 +38,11 @@ Settings for coverage can be found in [package.json](./package.json)
 
 #### To check test coverage
   ```shell
-  $ yarn test
+  $ npm test
   ```
 
 #### Code coverage failing to update?
 If you're having trouble getting an accurate code coverage report, or it's failing to provide updated results (i.e. you renamed files) you can try running
   ```
-  $ yarn test:clearCache
+  $ npm run test:clearCache
   ```