doc: Update description of rolreplication column

Since PostgreSQL 9.6, rolreplication no longer determines whether a role
can run pg_start_backup() and pg_stop_backup(), so remove that.

Add that this attribute determines whether a role can create and drop
replication slots.

Reported-by: Fujii Masao <masao.fujii@gmail.com>

doc/src/sgml/catalogs.sgml

@@ -1326,10 +1326,8 @@
       <entry><structfield>rolreplication</structfield></entry>
       <entry><type>bool</type></entry>
       <entry>
-       Role is a replication role. That is, this role can initiate streaming
-       replication (see <xref linkend="streaming-replication">) and set/unset
-       the system backup mode using <function>pg_start_backup</> and
-       <function>pg_stop_backup</>
+       Role is a replication role. A replication role can initiate replication
+       connections and create and drop replication slots.
       </entry>
      </row>
 
@@ -9852,10 +9850,8 @@ SELECT * FROM pg_locks pl LEFT JOIN pg_prepared_xacts ppx
       <entry><type>bool</type></entry>
       <entry></entry>
       <entry>
-       Role is a replication role. That is, this role can initiate streaming
-       replication (see <xref linkend="streaming-replication">) and set/unset
-       the system backup mode using <function>pg_start_backup</> and
-       <function>pg_stop_backup</>
+       Role is a replication role. A replication role can initiate replication
+       connections and create and drop replication slots.
       </entry>
      </row>
 

doc/src/sgml/ref/create_role.sgml

@@ -167,8 +167,11 @@ CREATE ROLE <replaceable class="PARAMETER">name</replaceable> [ [ WITH ] <replac
       <term><literal>NOREPLICATION</literal></term>
       <listitem>
        <para>
-        These clauses determine whether a role is allowed to initiate
-        streaming replication or put the system in and out of backup mode.
+        These clauses determine whether a role is a replication role.  A role
+        must have this attribute (or be a superuser) in order to be able to
+        connect to the server in replication mode (physical or logical
+        replication) and in order to be able to create or drop replication
+        slots.
         A role having the <literal>REPLICATION</> attribute is a very
         highly privileged role, and should only be used on roles actually
         used for replication. If not specified,