[RFC] doc: fix code snippet build warnings

[Tobin C. Harding]

Posting as RFC in the hope that someone knows how to massage sphinx
correctly to fix this patch.

Currently function kernel-doc contains a multi-line code snippet. This
is causing sphinx to emit 5 build warnings

	WARNING: Unexpected indentation.
	WARNING: Unexpected indentation.
	WARNING: Block quote ends without a blank line; unexpected unindent.
	WARNING: Block quote ends without a blank line; unexpected unindent.
	WARNING: Inline literal start-string without end-string.

And the snippet is not rendering correctly in HTML.

We can stop shpinx complaining by using '::' instead of the currently
used '``' however this still does not render correctly in HTML. The
rendering is [arguably] better but still incorrect. Sphinx renders two
function calls thus:

	:c:func:`rcu_read_lock()`;

The rest of the snippet does however have correct spacing.

Use '::' to pre-fix code snippet. Clears build warnings but does not
render correctly.

Signed-off-by: Tobin C. Harding <me@xxxxxxxx>
---

To view current broken rendering see

https://www.kernel.org/doc/html/latest/core-api/kernel-api.html?highlight=rcu_pointer_handoff#c.rcu_pointer_handoff

 include/linux/rcupdate.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index a6ddc42f87a5..cc10e772e3e9 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -568,7 +568,8 @@ static inline void rcu_preempt_sleep_check(void) { }
  * is handed off from RCU to some other synchronization mechanism, for
  * example, reference counting or locking.  In C11, it would map to
  * kill_dependency().  It could be used as follows:
- * ``
+ * ::
+ *
  *	rcu_read_lock();
  *	p = rcu_dereference(gp);
  *	long_lived = is_long_lived(p);
@@ -579,7 +580,6 @@ static inline void rcu_preempt_sleep_check(void) { }
  *			p = rcu_pointer_handoff(p);
  *	}
  *	rcu_read_unlock();
- *``
  */
 #define rcu_pointer_handoff(p) (p)
 
-- 
2.7.4