bundle: Move 'Linux sysctl' header to its own line

This fixes a copy/paste issue with 7232e4b (specs: introduce the
concept of a runtime.json, 2015-07-30, opencontainers#88).

Signed-off-by: W. Trevor King <[email protected]>

Author: wking

runtime-config-linux.md

@@ -131,7 +131,9 @@ Next parameters can be specified:
 
 Also known as cgroups, they are used to restrict resource usage for a container and handle
 device access.  cgroups provide controls to restrict cpu, memory, IO, and network for
-the container. For more information, see the [kernel cgroups documentation](https://www.kernel.org/doc/Documentation/cgroups/cgroups.txt)## Linux sysctl
+the container. For more information, see the [kernel cgroups documentation](https://www.kernel.org/doc/Documentation/cgroups/cgroups.txt).
+
+## Linux sysctl
 
 sysctl allows kernel parameters to be modified at runtime for the container.
 For more information, see [the man page](http://man7.org/linux/man-pages/man8/sysctl.8.html)