Move relevant docs out of downstream repos

[SJaffa]

Some new documentation has been written in https://github.com/hpcflow/matflow-new/tree/develop/docs but some of it is also relevant to HPCflow, so it should be moved to this upstream repo.

[SJaffa]

Checking which esctions have diverged. Starting form docs/source:

• _static - logo images are different, presumably the different names are handled somewhere?
• _templates
• contribute
• reference
  • template components
    • task_schemas.rst - matflow added jinja reference
  • cli.rst
  • config_file.rst - matflow added jinja reference
  • glossary.rst - lots of differences, some of them justified
  • index.rst - differences and doesn't exist in this repo
  • template_components.rst
  • workflows.rst
• user - lots of differences
  • getting_started - only in matflow
  • how_to
    • config.rst - many differences
    • environments.rst
    • index.rst - hpcflow has ref to resources
    • loops.rst
    • meta-tasks.rst
    • resources.rst - only in hpcflow
    • task_schemas.rst
    • template_components.rst
    • workflow_tempaltes.rst
    • workflows.rst
  • tutorials
    • index.rst - matflow has ref to jupyter notebooks
    • notebooks - only in matflow but hte notebook is material science specific, so that is ok
  • index - reference to getting_started
• conf.py - matflow added supported python versions
• installation.rst - lots of differences

I'll work through the simple ones now

[SJaffa]

Moved all shared info into the shared docs repo, made a few changes in response to feedback, waiting on Adam to rereview.