Add contribution guide and first issue badge

[wilsonbb]

Change Description

Adds a Contribution Guide within the Getting Started section of our docs. While we're here also adds a 'Good First Issue' github badge repo with a snippet courtesy of @dougbrn

[github-actions]

Before [d0af3ce]	After [020a114]	Ratio	Benchmark (Parameter)
33.5±0.2ms	34.5±0.3ms	1.03	benchmarks.time_prune_sync_workflow
33.4±1ms	33.3±0.07ms	1	benchmarks.time_batch

Click here to view all benchmarks.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.78%. Comparing base (bac4fe7) to head (b4901e6).
Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #424   +/-   ##
=======================================
  Coverage   95.78%   95.78%           
=======================================
  Files          25       25           
  Lines        1755     1755           
=======================================
  Hits         1681     1681           
  Misses         74       74           

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[dougbrn]

Looks good!