Init homepage 2.0

[hblitza]

Overall rewrite of mapproxy homepage using docusaurus:

• use main as default branch
• use gh-pages action for deployment
• integrate most content of previous homepage
• initiate feature slideshow (easy to extend)
• adds commercial support component (easy to add new support companies, see README)
• init resources page to collect tutorials, workshops and talks, maybe also example configurations

Live demo: https://hblitza.github.io/mapproxy-homepage/

@weskamm please give your opinion.

[weskamm]

Very nice @hblitza ! I just added some minor comments to the content which you may want to tackle. Great work!

[hblitza]

Thanks @weskamm that was indeed helpful. Fixed your findings.