docs: move other kAPI documents to core-api

There are a number of random documents that seem to be
describing some aspects of the core-api. Move them to such
directory, adding them at the core-api/index.rst file.
Signed-off-by: NMauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/86d979ed183adb76af93a92f20189bccf97f0055.1592918949.git.mchehab+huawei@kernel.orgSigned-off-by: NJonathan Corbet <corbet@lwn.net>

Documentation/core-api/index.rst

@@ -39,6 +39,8 @@ Library functionality that is used throughout the kernel.
    rbtree
    generic-radix-tree
    packing
+   bus-virt-phys-mapping
+   this_cpu_ops
    timekeeping
    errseq
 
@@ -82,6 +84,7 @@ more memory-management documentation in :doc:`/vm/index`.
    :maxdepth: 1
 
    memory-allocation
+   unaligned-memory-access
    dma-api
    dma-api-howto
    dma-attributes

arch/Kconfig

@@ -147,7 +147,7 @@ config HAVE_EFFICIENT_UNALIGNED_ACCESS
 	  problems with received packets if doing so would not help
 	  much.
 
-	  See Documentation/unaligned-memory-access.txt for more
+	  See Documentation/core-api/unaligned-memory-access.rst for more
 	  information on the topic of unaligned memory accesses.
 
 config ARCH_USE_BUILTIN_BSWAP