readwritesplit enables multi-statements regardless of the state of causal_reads

Readwritesplit requires that multi-statement execution is enabled if causal_reads is in use. Currently the capability is always enabled regardless of the state of causal_reads which changes the way that client connections behave compared to connecting directly to MariaDB.

The implication of this requirement is technically present in the documentation but it is not explicitly stated as a requirement. The protocol level capabilities should be more clearly explained and references to the connector parameters that enable similar behavior would be helpful.