Remove statement about search and optimistic concurrency control from 6.6 docs (#37876)

This turned out to not be true and is tackled by #37639 . That PR will be part of 6.7

Author: bleskes

docs/reference/docs/concurrency-control.asciidoc

@@ -85,10 +85,6 @@ returns:
 --------------------------------------------------
 // TESTRESPONSE[s/"_seq_no" : \d+/"_seq_no" : $body._seq_no/ s/"_primary_term" : 2/"_primary_term" : $body._primary_term/]
 
-
-Note: The <<search-search,Search API>> can return the `_seq_no` and `_primary_term`
-for each search hit by requesting the `_seq_no` and `_primary_term` <<search-request-docvalue-fields,Doc Value Fields>>.
-
 The sequence number and the primary term uniquely identify a change. By noting down 
 the sequence number and primary term returned, you can make sure to only change the
 document if no other change was made to it since you retrieved it. This