Fix display text for github link

s/"kernel/cgroup.c"/"kernel/cgroup/cgroup.c"/

Signed-off-by: Sebastian Fricke <sebastian.fricke.linux@gmail.com>

Cgroups/linux-cgroups-1.md

@@ -226,7 +226,7 @@ Early initialization of `cgroups` starts from the call of the:
 cgroup_init_early();
 ```
 
-function in the [init/main.c](https://github.com/torvalds/linux/blob/16f73eb02d7e1765ccab3d2018e0bd98eb93d973/init/main.c) during early initialization of the Linux kernel. This function is defined in the [kernel/cgroup.c](https://github.com/torvalds/linux/blob/master/kernel/cgroup/cgroup.c) source code file and starts from the definition of two following local variables:
+function in the [init/main.c](https://github.com/torvalds/linux/blob/16f73eb02d7e1765ccab3d2018e0bd98eb93d973/init/main.c) during early initialization of the Linux kernel. This function is defined in the [kernel/cgroup/cgroup.c](https://github.com/torvalds/linux/blob/master/kernel/cgroup/cgroup.c) source code file and starts from the definition of two following local variables:
 
 ```C
 int __init cgroup_init_early(void)