Spruce up the contribution guide.

[delucchi-cmu]

• Adds communication options, and embeds the HATS/LSDB calendar.
• Removes some duplicate/outdated installation instructions
• Points to LF code of conduct

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.38%. Comparing base (78fa073) to head (70a3707).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #531   +/-   ##
=======================================
  Coverage   97.38%   97.38%           
=======================================
  Files          43       43           
  Lines        1720     1720           
=======================================
  Hits         1675     1675           
  Misses         45       45           

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[github-actions]

Before [78fa073]	After [a0d0993]	Ratio	Benchmark (Parameter)
failed	failed	n/a	benchmarks.time_box_filter_on_partition
failed	failed	n/a	benchmarks.time_polygon_search
12.4±0.01s	12.4±0.06s	1.00	benchmarks.time_create_large_catalog
82.8±0.6ms	82.3±2ms	0.99	benchmarks.time_kdtree_crossmatch
1.88±0.01s	1.84±0.02s	0.98	benchmarks.time_create_midsize_catalog

Click here to view all benchmarks.

[delucchi-cmu]

Rendered preview:

https://lsdb--531.org.readthedocs.build/en/531/contact.html
https://lsdb--531.org.readthedocs.build/en/531/developer/contributing.html

[OliviaLynn]

Looks great!