community: Create CODE_OF_CONDUCT.md

[winder]

Summary

Add a code of conduct.

Test Plan

N/A

[codecov]

Codecov Report

Merging #82 (83d672a) into master (442791a) will increase coverage by 1.43%.
The diff coverage is 74.53%.

@@            Coverage Diff             @@
##           master      #82      +/-   ##
==========================================
+ Coverage   67.66%   69.09%   +1.43%     
==========================================
  Files          32       36       +4     
  Lines        1976     2417     +441     
==========================================
+ Hits         1337     1670     +333     
- Misses        570      654      +84     
- Partials       69       93      +24     

Impacted Files	Coverage Δ
conduit/data/block_export_data.go	100.00% <ø> (+92.30%)	⬆️
conduit/plugins/importers/algod/metrics.go	100.00% <ø> (ø)
...plugins/processors/filterprocessor/gen/generate.go	34.28% <ø> (ø)
pkg/cli/internal/list/list.go	20.75% <ø> (ø)
...lugins/exporters/postgresql/postgresql_exporter.go	66.66% <51.21%> (-11.54%)	⬇️
pkg/cli/cli.go	65.97% <65.97%> (ø)
conduit/pipeline/pipeline.go	66.09% <72.10%> (+0.64%)	⬆️
conduit/data/config.go	76.47% <76.47%> (ø)
conduit/plugins/importers/algod/algod_importer.go	87.38% <88.13%> (-0.93%)	⬇️
conduit/pipeline/errors.go	100.00% <100.00%> (ø)
... and 4 more

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