config-linux: specify mountlabel requirement for runtime

Ma Shimiao · Ma Shimiao · commit 203473cb1d14 · 2017-05-23T13:48:06.000+08:00
Signed-off-by: Ma Shimiao &lt;mashimiao.fnst@cn.fujitsu.com&gt;
diff --git a/config-linux.md b/config-linux.md
@@ -641,7 +641,9 @@ The values MUST be absolute paths in the [container namespace](glossary.md#conta
 
 ## <a name="configLinuxMountLabel" />Mount Label
 
-**`mountLabel`** (string, OPTIONAL) will set the Selinux context for the mounts in the container.
+**`mountLabel`** (string, OPTIONAL) will set the SELinux context for the mounts in the container.
+If `mountLabel` is specified and SELinux is enabled, the runtime MUST set `mountLabel` for the mounts in the container.
+For more information about SELinux, see  [SELinux documentation][selinux].
 
 ### Example
 
