Documentation: Destage TEE subsystem documentation

Add a separate documentation directory for TEE subsystem since it is a
standalone subsystem which already offers devices consumed by multiple
different subsystem drivers.

Split overall TEE subsystem documentation modularly where:
- The userspace API has been moved to Documentation/userspace-api/tee.rst.
- The driver API has been moved to Documentation/driver-api/tee.rst.
- The first module covers the overview of TEE subsystem.
- The further modules are dedicated to different TEE implementations like:
- OP-TEE
- AMD-TEE
- and so on for future TEE implementation support.

Acked-by: Rijo Thomas <Rijo-john.Thomas@amd.com>
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20231128072352.866859-1-sumit.garg@linaro.org

docs: put atomic*.txt and memory-barriers.txt into the core-api book

These files describe part of the core API, but have never been converted to
RST due to ... let's say local oppposition. So, create a set of
special-purpose wrappers to ..include these files into a separate page so
that they can be a part of the htmldocs build. Then link them into the
core-api manual and remove them from the "staging" dumping ground.

Acked-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Reviewed-by: David Vernet <void@manifault.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20220927160559.97154-7-corbet@lwn.net
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: Move kprobes.rst from staging/ to trace/

Kprobes contitutes a dynamic tracing technology and as such can be
moved alongside documentation of other tracing technologies.

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/8a09c01c64b2e003d5486c4f0c89740618f1bae4.1595331824.git.naveen.n.rao@linux.vnet.ibm.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: staging: use small font for literal includes

The normal font is too big to display 80 columns, causing extra
breaks to be added at weird places.

change to the footnotesize, as this would fit a little bit
better.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/fe2cc675ec69bfa50aa7e183dcd911077046b01f.1592918949.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: Add remaining Documentation/*.txt at staging/index.rst

There are a few text files that aren't yet at the docs building
system.

Add those to the staging/index.rst.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/35967d18de8b3ee480194acf68e62d515347c1e5.1592918949.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: staging: don't use literalinclude

Such directive cause troubles with PDF output.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/9a9043face7ace90e3616ba840a8e09cfc8f143f.1592203650.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: move remaining stuff under Documentation/*.txt to Documentation/staging

There are several files that I was unable to find a proper place
for them, and 3 ones that are still in plain old text format.

Let's place those stuff behind the carpet, as we'd like to keep the
root directory clean.

We can later discuss and move those into better places.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/11bd0d75e65a874f7c276a0aeab0fe13f3376f5f.1592203650.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>