document describing the CI/CD

Building the docs

$> cd /path/to/my/local/web_reflecivity/
$> conda activate webrefl  # or "make conda" ifenvironment "webrefl" was never created.
$> make devdocs

• To view the document, point the browser to file:///path/to/my/local/web_reflecivity/dev-docs/_build/html/devops/index.html
• a PDF printout of the document is here: devops.pdf