R1:699228c73b74

Address some New Search Configuration Errata

Summary:
[ ] Write an "Upgrading: ..." guidance task with narrow instructions for installs that are upgrading.
[ ] Do we need to add an indexing activity (T11932) for installs with ElasticSearch?
[ ] We should more clearly detail exactly which versions of ElasticSearch are supported (for example, is ElasticSearch <2 no longer supported)? From T9893 it seems like we may //only// have supported ElasticSearch <2 before, so are the two regions of support…