Add Theodolite docs

Depends on !161 (merged).

See #141 for the planned documentation structure.

This MR covers the following points to provide a basis for future extension of the docs:

• Support for local docs building
• Basic navigation structure
• Page: Home
• Page: Getting started
  • Fix creation of ConfigMap
  • Fix capitalization of execution status (if changed)
  • Add next steps
• Page: Installation
  • Add helm installation instructions (Fix #181 (closed))
• Page: Running Benchmarks
  • Page: Creating Executions
  • Explain results
  • Explain benchmark status (!176 (merged))
• Page: Creating Benchmarks
  • Explain fileSystem and configMap resource sets (!171 (merged))
  • Explain infrastructure field (!197 (merged))
• API Reference
  • Fix patcher page (spelling/correctness)
  • Ensure CRD docs are up-to-date (fix #237 (closed))