Added .patch to zlib patch

git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@2585 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689

chapter06/zlib-inst.xml

@@ -7,7 +7,7 @@
 that, though difficult to take advantage of, should be taken care of. Do
 so by applying this patch:</para>
 
-<para><screen><userinput>patch -Np1 -i ../zlib-&zlib-patch-version;</userinput></screen></para>
+<para><screen><userinput>patch -Np1 -i ../zlib-&zlib-patch-version;.patch</userinput></screen></para>
 
 <para>Prepare Zlib to be compiled:</para>