Add doc comment that installation.sgml can't use xrefs.

diff --git a/doc/src/sgml/installation.sgml b/doc/src/sgml/installation.sgml
index 70f930c57dab882a8eafda4a232f8ca7bf8a204f..5c719d5a0ab1dc7c526abbb1e6d1113ae18c589e 100644 (file)
--- a/doc/src/sgml/installation.sgml
+++ b/doc/src/sgml/installation.sgml
@@ -1,4 +1,10 @@
 <!-- doc/src/sgml/installation.sgml -->
+<!--
+
+Use </link> not just </> so INSTALL.html can be created without links
+to the main documentation.  Don't use <xref>.
+
+-->
 
 <chapter id="installation">
  <title><![%standalone-include[<productname>PostgreSQL</>]]>