docs: Cleanup running Feast in production, fix links, call out Slack more

[adchia]

What this PR does / why we need it:

Which issue(s) this PR fixes:

Fixes #

[codecov-commenter]

Codecov Report

Base: 67.10% // Head: 76.13% // Increases project coverage by +9.02% 🎉

Coverage data is based on head (9844681) compared to base (bf6e7f4).
Patch has no changes to coverable lines.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3163      +/-   ##
==========================================
+ Coverage   67.10%   76.13%   +9.02%     
==========================================
  Files         175      211      +36     
  Lines       15903    17854    +1951     
==========================================
+ Hits        10672    13593    +2921     
+ Misses       5231     4261     -970     

Flag	Coverage Δ
integrationtests	66.93% <ø> (-0.17%)	⬇️
unittests	58.28% <ø> (?)

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

Impacted Files	Coverage Δ
...on/feast/infra/materialization/snowflake_engine.py	92.13% <0.00%> (-0.46%)	⬇️
...offline_stores/contrib/spark_repo_configuration.py	100.00% <0.00%> (ø)
...line_stores/contrib/athena_offline_store/athena.py	38.50% <0.00%> (ø)
...line_stores/contrib/postgres_repo_configuration.py	100.00% <0.00%> (ø)
.../online_stores/contrib/hbase_repo_configuration.py	100.00% <0.00%> (ø)
...s/contrib/spark_offline_store/tests/data_source.py	40.74% <0.00%> (ø)
...b/cassandra_online_store/cassandra_online_store.py	40.00% <0.00%> (ø)
...ores/contrib/trino_offline_store/trino_type_map.py	6.66% <0.00%> (ø)
...s/contrib/trino_offline_store/connectors/upload.py	8.97% <0.00%> (ø)
sdk/python/feast/loaders/yaml.py	18.18% <0.00%> (ø)
... and 99 more

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[achals]

/lgtm

[feast-ci-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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