update readme: we also support recovery.img
update readme: we also support recovery.img

cfig/Android_boot_image_editor,cfig/Nexus_boot_image_editor,cfig/Android_boot_image_editor,cfig/Android_boot_image_editor,cfig/Nexus_boot_image_editor,cfig/Android_boot_image_editor,cfig/Nexus_boot_image_editor,cfig/Android_boot_image_editor,cfig/Android_boot_image_editor,cfig/Nexus_boot_image_editor