docs: Improve README Formatting

[ueman]

Link to the rendered README https://github.com/ueman/home_widget/blob/7f255317b5f69bdd880708de12e0cdf32897e5a4/README.md

This uses the <kbd> HTML tag to render menu paths a bit nicer, see

I've also fixed and added syntax highlighting to a broken code fence.

[ueman]

@ABausG friendly ping to review these couple minor fixes

[ABausG]

Thanks for this! Love the kbd tags.

Just a small question regarding a line change you added where I believe something got mixed up

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (daea9c1) 100.00% compared to head (4d066a2) 100.00%.
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #204   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            2         2           
  Lines           69        73    +4     
=========================================
+ Hits            69        73    +4     

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