Add better documentation

[sebgrebe]

To make it easier to onboard devs in the future, we want to:

• [x] Add contribute.md with contribution guidelines
• [x] Add Readme.md to look more like this example
• [x] Create setup.md (or similar) with instructions on how to run the project locally
• [x] Add page with overview of third party tools we're using (algolia etc)
• [x] Add a CODE_OF_CONDUCT.md

[sebgrebe]

Third party tools list is in internal document