Feature/#206 docs intro text

[nesnoj]

Closes #206

• Adds project infos and links
• Moves infos on the region from ESM docs to intro
• Removes under construction notice
• Changes main menu ordering
• Adjusts heroes (top headlines)
• Fixes top menu
• Adds RLI logo to header
• Changes theme color

Unfortunately, I could not make the RLI logo to align right, apparently in the material theme the horizontal aligning doesn't work as expected in general :(.

Preview

Includes docs on data #208, so please merge #208 first!