Contribute support to themes

[timvink]

See overview of mkdocs themes and contribute native support for this plugin (by adding CSS to the theme).

Shortlist:

• alabaster
• mkdocs-material
• mkdocs-bootstap
• mkdocs-windmill
• mkdocs-gitbook-theme

[timvink]

After discussing with squidfunk from mkdocs-material, contrast is quite important. I'll wait and see if this plugin gains some traction, and if it does open an issue to the other themes for consideration.