Setup initial documentation

[patrickersing]

This PR creates the initial documentation for TrixiShallowWater.jl.

ToDo:

• Authors list
• Tutorials (start with around three)
  • something with wet/dry
  • something with multiple layers
  • something that uses TrixiBottomTopography.jl
• Installation page
• Contributing
• Code of conduct
• Development and testing
• security.md

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.32%. Comparing base (2280912) to head (8c83cda).
Report is 1 commits behind head on main.

Additional details and impacted files

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  Coverage   99.32%   99.32%           
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  Files          60       60           
  Lines        2794     2794           
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  Hits         2775     2775           
  Misses         19       19           

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[patrickersing]

@andrewwinters5000 very nice tutorial!
I think it's looks quite good already. I have a few smaller comments and a suggestion how we could streamline the tutorial by setting up everything for the final time directly.

[andrewwinters5000]

Some small comments as we move closer to the finish line for the docs.

[andrewwinters5000]

better figure for Okushiri tutorial

[andrewwinters5000]

Just one final comment and I will push an update to the authors list.

[andrewwinters5000]

LGTM, Great work @patrickersing ! I think we are ready to pull the ripcord

[andrewwinters5000]

Last new figure