Ring buffer section now resides under "other" topic, since the
ring buffer type is a general purpose type (like the singly and
doubly linked list types), rather than a kernel-specific type.
Enhances ring buffer section to improve content and improve
consistency with the form used elsewhere in the Kernel Primer.
Also corrects a minor error in the ring buffer API documentation.
Change-Id: Icaa8661524f80e31f173adee859844cadb38967f
Signed-off-by: Allan Stephens <allan.stephens@windriver.com>
11a1bb4125