Improve documentation and create module/wrapper templates

[irm-codebase]

We need a better approach to documentation.

• [x] Documentation
  • [x] Choose a provider (either read the docs or github pages)
  • [ ] Find a way to link module / wrapper documentation
  • [x] Add a 'how to contribute page' with guidelines
• [ ] Templates (cookiecutter or similar)
  • [ ] Template for modules
  • [ ] Template for wrappers

[irm-codebase]

Documentation is complete thanks to #26 Available here https://calliope-project.github.io/ec_modules/

We still need to link each module to the website, but for now it's good enough.

Templates for modules are still missing.

[irm-codebase]

Added templates with clipper and improved the documentation. Creating new modules with standard configuration / licensing / etc is quite easy now.