feat: print usage when running patch without args

[eseidel]

Very low priority. I just ran across this while trying to
test the patch tool for a user.

[eseidel]

I chose not to try and write any tests. I did test manually.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 17 lines in your changes are missing coverage. Please review.

Project coverage is 96.07%. Comparing base (7361089) to head (b8f9eb6).

❗ Current head b8f9eb6 differs from pull request most recent head 0ebe020. Consider uploading reports for the commit 0ebe020 to get more accurate results

Files	Patch %	Lines
patch/src/main.rs	0.00%	17 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #124      +/-   ##
==========================================
- Coverage   96.59%   96.07%   -0.53%     
==========================================
  Files          20       21       +1     
  Lines        2882     2803      -79     
==========================================
- Hits         2784     2693      -91     
- Misses         98      110      +12     

Flag	Coverage Δ
patch	36.95% <0.00%> (-8.38%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.