Restructure docs and host using ReadTheDocs

[ManavalanG]

Pull request

Please fill in the checklist below and comment as needed.

• [x] Was code modified? Briefly describe. No
• [x] Was documentation modified? Briefly describe. Yes. Please see below.
• [x] Is this a bug-fix? Briefly describe. No
• [x] Is this a feature addition? Briefly describe. Yes, partly. Builds doc using mkdocs and hosts using readthedocs
• [x] Did you modify QuaC-Watch config file? If so, did you modify multiqc template configs/multiqc_config_template.jinja2 and script src/quac_watch/create_mutliqc_configs.py as necessary? No
• [x] Did you perform system-level testing manually as described in master readme doc? Did it pass completely? If not why? No
• [x] Updated Changelog.md file with change logs in recommended format?

Anything else reviewer should know?

Main goal of this PR is to restructure the docs to make it clearer to non-Cheaha users, update documentation to reflect recent CLI option changes, and host docs publicly using readthedocs. QuaC doc is now available at https://quac.readthedocs.io/, which is based on the branch in this PR.

• Readme.md has grown bigger and became difficult to navigate. Especially for non-Cheaha users. So documentation in readme.md is now restructured to break into multiple files and is now easier to consume.
  • Makes the doc generic to non-Cheaha users
  • Identifies parts of the docs that are specific to Cheaha or CGDS users
• Updates doc to reflect changes made in #59
• Now hosts doc for "Sample QC review system". Its copy in MOO will be removed after this PR is complete.
• Uses mkdocs to create static site for documentation.
  • Setup in this repo was used - https://github.com/ManavalanG/mana_random_notes/, which was based on https://github.com/readthedocs-examples/example-mkdocs-basic/.
• Hosts QuaC docs using ReadTheDocs
  • Repo is made public to make this happen.
  • Setup in this repo was used - https://github.com/ManavalanG/mana_random_notes/, which was based on https://github.com/readthedocs-examples/example-mkdocs-basic/.
• Items not directly related to docs restructuring or hosting
  • Adds github action to identify broken links in markdown files
  • Migrates Gitlab MR template to Github PR template
  • Removes html files that were part of system testing input data. They were not necessary for system testing and they heavily inflate languages-used stats in github.
  • Adds note to readme on quac's former residence in UAB-gitlab.

[ManavalanG]

@wilkb777 Ready for your review again.

Note: Github markdown-link-check actions still fails with this public link - https://gatk.broadinstitute.org/hc/en-us/articles/360035531972-PED-Pedigree-format. Not sure why.

[ManavalanG]

@wilkb777 Updated docs to make it clear that quac is built to use with human data.