CBL 3.1 and SGW lower than 3.1 replication should use default collection

We have had reports of users being confused about using CBL 3.1 with Sync Gateway (SGW) that does not support S&C, ending up in a dead end and not with an actionable error message. To improve on this, the Couchbase Lite Replication documentation needs to be updated to address these compatibility issues. Provide guidance for users encountering these issues. Specifically, when initiating replication between Couchbase Lite (CBL) and a Scopes and Collections incompatible version of SGW, the documentation should emphasize the use of the default collection as a fallback option.

Additionally, we need to mention that App Services does not currently support Scopes and Collections. Users who wish to utilize CBL 3.1 and above with our Capella App Services should explicitly use the default collection as well.

Requirements:

• Highlight that when initiating replication between a S&C incompatible version of Sync Gateway and Couchbase Lite, the default collection should be used. Provide a code example for each of the supported platforms/languages demonstrating how to add the default collection in the replication configuration. E.g. for Java the replication config lives here. 
  • Collaborate with the Couchbase Lite team to get code samples for each language as to how to use default Collection config in code.
  • Additionally, emphasize that users who want to use CBL 3.1 and above with App Services should explicitly use the default collection. Provide instructions and a code example to illustrate how to configure the replication with the default collection explicitly.

• State that App Services does not currently support custom Scopes and Collections, so expectations for users are set up front about what we support with the 3.1 release, e.g. when they first encounter the new release, e.g. in What's new and App Services Docs. State that Scopes and Collections CBL 3.1.x releases can still be used with App Services with the default collection API (as above). Clarify the compatibility between Couchbase Lite and Sync Gateway versions regarding Scopes and Collections. Include which versions of Sync Gateway are compatible with Scopes and Collections in Couchbase Lite.