Update metadata

[jni]

• Move napari folder to napari-hub folder for now
• Update readme to match description
• Remove DESCRIPTION file, can just fall back on README
• Add Transformations category to manifest
• Docs build uses README instead of DESCRIPTION

Closes #63

[codecov-commenter]

Codecov Report

Merging #74 (503142b) into main (960fcc7) will not change coverage.
The diff coverage is n/a.

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@@           Coverage Diff           @@
##             main      #74   +/-   ##
=======================================
  Coverage   85.96%   85.96%           
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  Files           4        4           
  Lines         171      171           
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  Hits          147      147           
  Misses         24       24