109 updating documentation for v1.0

[budschi]

I added some content to the docs:

• Home/index.md
• Explanation:
  • Levels of schemas,
  • Schemas and Readers (just a place holder)
• How-to Guids:
  • Install this Plugin
  • Use this Plugin (just a place holder)
  • Develop this Plugin (just a place holder)
  • Contact (analg to the simulations plugin from Area C)

Todos:

• [ ] review this new documents
• [ ] add content to "Schemas and Readers"
• [ ] add content to "Use this Plugin"
• [ ] add content to "Develop this Plugin"

Questions:

• Do we put something into "References" and "Tutorials"?
• The documentation of NOMAD-Materials-Processing is quite analog to this one. We should consicer pushing the general stuff to the central NOMAD docs Domain-specific Examples!?

[budschi]

• [x] explaination: XRD @ka-sarthak
• [x] how-tos same as in materials processing
  • [x] as is : XRD @ka-sarthak (drag and drop a file), show that it gets parsed automatically
  • [x] inherit: yaml plus sth extra in XRD @ka-sarthak
  • [x] python: @hampusnasstrom
• [x] contact: topics remove @budschi