Overhaul the PelePhysics docs (currently very out of date and disorganized)

[baperry2]

Overall objective: make the documentation organization match the code organization

• [x] Quickstart/Installation
• [ ] Introduction: overview of code functionality and design
• [ ] Major source components
  • [ ] EOS
  • [x] Transport
  • [ ] Reactions
  • [x] Soot
  • [x] Spray
  • [ ] Radiation
  • [ ] Utility
    • [x] PMF
    • [x] Filter
    • [ ] Diagnostics
    • [ ] Plt File Management
    • [x] Turbulent inflows (high priority), see #401. PR: #489
• [ ] Mechanisms: provide references
• [ ] Support codes
  • [x] CEPTR
  • [x] MechanismPAH
  • [x] Turbulent Inflow
  • [ ] PMF Generator
  • [x] liquidProp
• [ ] Testing
  • [ ] EosEval
  • [ ] ReactEval
  • [ ] ...