Add worst case scenario rollback plan (#1069)

Fixes: https://github.com/usds/justice40-tool/issues/947

This is ensuring we at least have some way to rollback in the worst case
scenario of the data being corrupted somehow, and our upstream data
sources being down in a way that prevents us from regenerating any
datasets. See
https://github.com/usds/justice40-tool/issues/946#issuecomment-989155252
for an analysis of the different ways the pipeline can fail and their
impacts.

This guide is very brittle to pipeline changes, and should be considered
a temporary solution for the worst case. I think that someday the github
actions should run more frequently and write to different paths, perhaps
with a timestamp. That would make rolling back more straightforward, as
a previous version of the data would already exist at some path in s3.

docs/operations/README.md

@@ -0,0 +1,3 @@
+# Operations Guides
+
+This directory should have guides for operating any services that are being supported by the Justice40 team.