Make the text regarding the new merge policy for stable/10

less hard to miss.

Submitted by:	rwatson
Sponsored by:	The FreeBSD Foundation

en_US.ISO8859-1/articles/committers-guide/article.xml

@@ -1297,6 +1297,17 @@ You need a Passphrase to protect your secret key.</screen>
 	  <title>Selecting the Source and Target for
 	    <literal>stable/9</literal> and Older</title>
 
+	  <para>For <literal>stable/9</literal> and earlier,
+	    a different strategy was used, distributing mergeinfo
+	    around the tree so that merges could be performed without
+	    a complete checkout.  This procedure proved extremely
+	    error-prone, with the convenience of partial checkouts for
+	    merges significantly outweighed by the complexity of
+	    picking mergeinfo targets.  The below describes this
+	    now-obsoleted procedure, which should be used
+	    <emphasis>only for merges prior to
+	      <literal>stable/10</literal></emphasis>.</para>
+
 	  <para>Because of mergeinfo propagation, it is important to
 	    choose the source and target for the merge carefully to
 	    minimise property changes on unrelated directories.</para>