Rewrite wiki documentation

[samrocketman]

Include documentation for:

• End users (developers whose projects get built by Jenkins)
• Implementors (i.e. Jenkins admins)

Document new pipelines usage.

Document, update, or delete the following pages:

• [ ] https://github.com/samrocketman/jervis/wiki/Admin-Guide
• [ ] https://github.com/samrocketman/jervis/wiki/Build-overview
• [x] https://github.com/samrocketman/jervis/wiki/Developing-Jervis (maybe delete)
• [ ] https://github.com/samrocketman/jervis/wiki/Labels-for-Jenkins-Agents
• [ ] https://github.com/samrocketman/jervis/wiki/Pipeline-support
• [ ] https://github.com/samrocketman/jervis/wiki/Quickstart (maybe delete)
• [ ] https://github.com/samrocketman/jervis/wiki/Secure-secrets-in-repositories
• [x] https://github.com/samrocketman/jervis/wiki/Specification-for-lifecycles-file
• [x] https://github.com/samrocketman/jervis/wiki/Specification-for-platforms-file
• [x] https://github.com/samrocketman/jervis/wiki/Specification-for-toolchains-file
• [ ] https://github.com/samrocketman/jervis/wiki/Supported-Tools
• [ ] https://github.com/samrocketman/jervis/wiki/User-Guide

[samrocketman]

Finished Updating:

• Home page
• Supported languages
• Matrix job support

[samrocketman]

Renamed https://github.com/samrocketman/jervis/wiki/Developing-Jervis to https://github.com/samrocketman/jervis/wiki/Development-Guide