Adding basic README and beginning of structure for docs

update to .gitlab-ci.yml

• add in the pages section for building mkdocs (untested as i've never used this feature before)

adding build-docs.py

• a basic script that will
  • copy the main readme into docs as index.md
  • search through submodule dirs for README files
  • copy those into the appropriate destination in docs

adding mkdocs.yml

• defines the basic structure of the documentation site for us with mkdocs
• note this will need to be manually updated for any new README created in submodules

Adding basic README and beginning of structure for docs

• Basic README and corresponding index in /docs
• copied documentation from docs.drupal.org in md format inot /docs
• copied the README's found in submodules into /docs with mirrored structure as index.md files