Refactor documentation about privileges to centralize the info.

Expand section 5.6 "Privileges" to include the full definition of
each privilege type, and an explanation of aclitem privilege displays,
along with some helpful summary tables.  Most of this material came
out of the GRANT reference page, although some of it is new.
Adjust a bunch of links that were pointing to GRANT to point to 5.6.

Fabien Coelho and Tom Lane, reviewed by Bradley DeJong

Discussion: https://postgr.es/m/alpine.DEB.2.21.1807311735200.20743@lancre

doc/src/sgml/ref/revoke.sgml

@@ -177,14 +177,6 @@ REVOKE [ ADMIN OPTION FOR ]
  <refsect1 id="sql-revoke-notes">
   <title>Notes</title>
 
-  <para>
-   Use <xref linkend="app-psql"/>'s <command>\dp</command> command to
-   display the privileges granted on existing tables and columns.  See <xref
-   linkend="sql-grant"/> for information about the
-   format.  For non-table objects there are other <command>\d</command> commands
-   that can display their privileges.
-  </para>
-
   <para>
    A user can only revoke privileges that were granted directly by
    that user.  If, for example, user A has granted a privilege with
@@ -244,6 +236,11 @@ REVOKE [ ADMIN OPTION FOR ]
     lead to revoking privileges other than the ones you intended, or not
     revoking anything at all.
    </para>
+
+   <para>
+    See <xref linkend="ddl-priv"/> for more information about specific
+    privilege types, as well as how to inspect objects' privileges.
+   </para>
  </refsect1>
 
  <refsect1 id="sql-revoke-examples">
@@ -293,9 +290,10 @@ REVOKE admins FROM joe;
  <refsect1>
   <title>See Also</title>
 
-  <simpara>
-   <xref linkend="sql-grant"/>
-  </simpara>
+  <simplelist type="inline">
+   <member><xref linkend="sql-grant"/></member>
+   <member><xref linkend="sql-alterdefaultprivileges"/></member>
+  </simplelist>
  </refsect1>
 
 </refentry>