Stale search filtering documentation

[lmsurpre]

Describe the bug
In #1351 and #1499 we introduced config changes which affect how to configure the server's search filtering capabilities.
However, we forgot to update the corresponding documentation at https://ibm.github.io/FHIR/guides/FHIRSearchConfiguration#12-configuration-filtering-of-search-parameters

Additionally, now that we have a $reindex operation, we should add information on how to use that to this guide as well.
We can probably lift most of that from the Reindex resources section of the 4.5.0 release notes