Fix readme

[jhdark]

Proposed changes

Fix for #36

Updating the README to fix all the codeblock with outdated code and added some more info newer features like meshtags

Types of changes

What types of changes does your code introduce to foam2dolfinx?

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Code refactoring
• Documentation Update (if none of the other choices apply)
• New tests

Checklist

• Unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

Further comments

If this is a relatively large or complex change, kick off the discussion by explaining why you chose the solution you did and what alternatives you considered, etc...

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.50%. Comparing base (0a06db8) to head (85ee749).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #38   +/-   ##
=======================================
  Coverage   98.50%   98.50%           
=======================================
  Files           3        3           
  Lines         268      268           
=======================================
  Hits          264      264           
  Misses          4        4           

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