Note explicitly that hash indexes are also not replicated because they're not

WAL-logged. Make the notice about the lack of WAL-logging more visible by
making it a <caution>. Also remove the false statement from hot standby
caveats section that hash indexes are not used during hot standby.

doc/src/sgml/high-availability.sgml

@@ -1845,8 +1845,7 @@ LOG:  database system is ready to accept read only connections
    <listitem>
     <para>
      Operations on hash indexes are not presently WAL-logged, so
-     replay will not update these indexes.  Hash indexes will not be
-     used for query plans during recovery.
+     replay will not update these indexes.
     </para>
    </listitem>
    <listitem>

doc/src/sgml/indices.sgml

@@ -187,14 +187,15 @@ CREATE INDEX <replaceable>name</replaceable> ON <replaceable>table</replaceable>
 </synopsis>
   </para>
 
-  <note>
+  <caution>
    <para>
     Hash index operations are not presently WAL-logged,
     so hash indexes might need to be rebuilt with <command>REINDEX</>
-    after a database crash.
-    For this reason, hash index use is presently discouraged.
+    after a database crash. They are also not replicated over streaming or
+    file-based replication.
+    For these reasons, hash index use is presently discouraged.
    </para>
-  </note>
+  </caution>
 
   <para>
    <indexterm>