message: Add a 'Package Managers' section to the coding guidelines
diff: # Coding Guidelines
  +## Package managers
  +
  +The default package manager for the Keycloak UI projects is NPM. There are several reasons why NPM is used over other package managers (such as Yarn and PNPM):
  +
  +- It comes included with NodeJS by default, meaning it does not have to be installed manually.
  +- Most contributors are familiar with the NPM ecosystem and tooling.
  +- We do not use any of the 'advanced' features of other package managers (such as [Yarn's PNP](https://yarnpkg.com/features/pnp)).
  +
  +If you submit a pull request that changes the dependencies, make sure that you also update the `package-lock.json` as well.
  +
  ## Typescript
  