[DOCS] Refer back to index API for full-document updates in _update API section (#28677)
[DOCS] Refer back to index API for full-document updates in _update API section (#28677)

This clarifies how full-document updates are performed in ES.
strapdata/elassandra,strapdata/elassandra,strapdata/elassandra,strapdata/elassandra,strapdata/elassandra,vroyer/elassandra,vroyer/elassandra,vroyer/elassandra