sched: Documentation/sched-rt-group: Fix style issues & bump version

- add missing closing bracket
- fix two 80-chars issues (as the rest of the document adheres to it)
- bump a reference to kernel version, so the document does not feel aged

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1245580359-4465-1-git-send-email-w.sang@pengutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>