Add a note about the inline strip patch feature.

Sponsored by:	Absolight

en_US.ISO8859-1/books/porters-handbook/makefiles/chapter.xml

@@ -1973,6 +1973,20 @@ EXTRACT_ONLY=	source.tar.gz</programlisting>
 	<varname>PATCHDIR</varname> directory&mdash;that directory may
 	not be writable.</para>
 
+      <tip>
+	<para>If there are multiple patches and they need mixed values
+	  for the strip parameter, it can be added alongside the patch
+	  name in <varname>PATCHFILES</varname>, e.g:</para>
+
+	<programlisting>PATCHFILES=	patch1 patch2:-p1</programlisting>
+
+	<para>This does not conflict with <link
+	    linkend="porting-master-sites-n">the master site grouping
+	    feature</link>, the following also works:</para>
+
+	<programlisting>PATCHFILES=	patch2:-p1:source2</programlisting>
+      </tip>
+
       <note>
 	<para>The tarball will have been extracted alongside the
 	  regular source by then, so there is no need to explicitly