descriptions about xdcr scramsha authentication are inaccurate

There are several issues with the documentation on scramsha authentication in the following section:

https://developer.couchbase.com/documentation/server/5.5/xdcr/xdcr-managing-security.html

1. The UI snapshot is out of date, which needs to be updated to the 5.5 version.

2. "By default, XDCR uses the Simple Authentication and Security Layer (SASL) framework to determine how username and password should be sent: either as plain text, or as encrypted by one of the members of the Salted Challenge Response Authentication Mechanism family of hash functions; which are SCRAM-SHA1, SCRAM-SHA256, and SCRAM-SHA512."

This is not correct.

By default, xdcr uses SASL.

If half secure mode is selected, ("Enable secure connection" checkbox is checked, and "Half" radio button is selected on UI), xdcr uses SCRAM-SHA.

If full secure mode is selected, ("Enable secure connection" checkbox is checked, and "Full" radio button is selected on UI), xdcr uses TLS encryption.

The texts need to be modified and re-arranged accordingly.