Combine these Metrics Platform wiki pages:
- How to/Getting Started: This is helpful content for maintainers, so let's keep it as-is but re-organize it as part of the maintainer docs.
- How to/Choose your language/Setup for JS: No unique content. Redirected to How to/Getting Started.
- How to/Choose your language/Setup for Java: Moved unique content and redirected to How to/Getting Started.
- How to/Choose your language/Setup for PHP: No unique content. Redirected to How to/Getting Started.