Redo: add contributing_to_documentation section documenting NWChemEx

[yzhang-23]

Redo the job in PR#79 (the new source file had not been added accidentally): A new section of "Contributing to NWChemEx Documentation" is added under "Documenting NWChemEx" in the development documentation. In this section the basic orgnization of the NWChemEx documentation system is described and instructions on how to update and build the documentation are given.

PR Type

• [ ] Breaking change
• [ ] Feature
• [ ] Patch
• [X] Documentation

Brief Description

Not In Scope

PR Checklist

• [X] Documentation (comments, API, user, design, and developer as applicable)
  • API
  • User
  • Design
  • Developer
• [ ] Testing (unit, integration, performance, as applicable)
  • Unit
  • Integration
  • Performance
• [ ] Code adheres to organization standards
  • C++
  • Python
  • Doxygen Conventions
  • reST Conventions

TODOs

• [X] Add a new section of "Contributing to NWChemEx Documentation" under "Documenting NWChemEx" in the development documentation.

[ryanmrichard]

🚀 [bumpr] Bumped! New version:v0.0.9 Changes:v0.0.8...v0.0.9