docs: clarify that CREATE DATABASE does not copy db permissions

That is, those database permissions set by GRANT.

Diagnosed-by: Joseph Nahmias

Discussion: https://postgr.es/m/20200614072613.GA21852@nahmias.net

Backpatch-through: 9.5

doc/src/sgml/ref/create_database.sgml

@@ -236,8 +236,8 @@ CREATE DATABASE <replaceable class="parameter">name</replaceable>
 
    <para>
     Database-level configuration parameters (set via <xref
-    linkend="sql-alterdatabase"/>) are not copied from the template
-    database.
+    linkend="sql-alterdatabase"/>) and database-level permissions (set via
+    <xref linkend="sql-grant"/>) are not copied from the template database.
    </para>
 
   <para>