futex-requeue-pi.txt: standardize document format

Each text file under Documentation follows a different
format. Some doesn't even have titles!

Change its representation to follow the adopted standard,
using ReST markups for it to be parseable by Sphinx:

- promote level for the document title;
- mark literal blocks.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/futex-requeue-pi.txt

@@ -1,5 +1,6 @@
+================
 Futex Requeue PI
-----------------
+================
 
 Requeueing of tasks from a non-PI futex to a PI futex requires
 special handling in order to ensure the underlying rt_mutex is never
@@ -20,7 +21,7 @@ implementation would wake the highest-priority waiter, and leave the
 rest to the natural wakeup inherent in unlocking the mutex
 associated with the condvar.
 
-Consider the simplified glibc calls:
+Consider the simplified glibc calls::
 
 	/* caller must lock mutex */
 	pthread_cond_wait(cond, mutex)
@@ -53,7 +54,7 @@ In order to support PI-aware pthread_condvar's, the kernel needs to
 be able to requeue tasks to PI futexes.  This support implies that
 upon a successful futex_wait system call, the caller would return to
 user space already holding the PI futex.  The glibc implementation
-would be modified as follows:
+would be modified as follows::
 
 
 	/* caller must lock mutex */