Testapp README cleanup

Author: NullVoxPopuli

test-app/README.md

@@ -16,7 +16,7 @@ You will need the following things properly installed on your computer.
 
 * `git clone <repository-url>` this repository
 * `cd test-app`
-* `yarn install`
+* `pnpm install`
 
 ## Running / Development
 
@@ -35,8 +35,8 @@ Make use of the many generators for code, try `ember help generate` for more det
 
 ### Linting
 
-* `yarn lint`
-* `yarn lint:fix`
+* `pnpm lint`
+* `pnpm lint:fix`
 
 ### Building