docbook: move pipe and splice to filesystems docbook

Move pipes and splice docbook to filesystems book.
kernel-api book is huge (10x most other books) & slow to process.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/DocBook/filesystems.tmpl

@@ -398,4 +398,24 @@ an example.
 
   </chapter>
 
+  <chapter id="splice">
+      <title>splice API</title>
+  <para>
+	splice is a method for moving blocks of data around inside the
+	kernel, without continually transferring them between the kernel
+	and user space.
+  </para>
+!Ffs/splice.c
+  </chapter>
+
+  <chapter id="pipes">
+      <title>pipes API</title>
+  <para>
+	Pipe interfaces are all for in-kernel (builtin image) use.
+	They are not exported for use by modules.
+  </para>
+!Iinclude/linux/pipe_fs_i.h
+!Ffs/pipe.c
+  </chapter>
+
 </book>