[DOCS] clarify behaviour when routing is required and no routing value is specified
[DOCS] clarify behaviour when routing is required and no routing value is specified

This note in the delete api about broadcasting to all shards is a leftover that should have been removed when the broadcasting feature was removed

Relates to #10136

strapdata/elassandra-test,strapdata/elassandra-test,strapdata/elassandra-test,strapdata/elassandra-test,strapdata/elassandra-test,strapdata/elassandra-test,strapdata/elassandra-test