Add stable to Manjaro URL

src/manjaro.ipxe

@@ -25,7 +25,7 @@ goto mirror_cfg
 :mirror_cfg
 set flavor_root ${flavor}
 iseq ${flavor} net && set flavor_root netinstall ||
-set manjaro_initrd http://sourceforge.net/projects/manjarolinux/files/release/${manjaro_version}/${flavor_root}/manjaro-${flavor}-${manjaro_version}-x86_64.iso/download
+set manjaro_initrd http://sourceforge.net/projects/manjarolinux/files/release/${manjaro_version}/${flavor_root}/manjaro-${flavor}-${manjaro_version}-stable-x86_64.iso/download
 goto manjaro_boot
 
 :manjaro_boot