coresight: docs: Create common sub-directory for coresight trace.

There are two files in the Documentation/trace directory relating to
coresight, with more to follow, so create a Documentation/trace/coresight
directory and move existing files there. Fixup index to reference
new location.

Update MAINTAINERS to reference this sub-directory rather than the
individual files.

Signed-off-by: Mike Leach <[e-mail]>
Reviewed-by: Mathieu Poirier <[e-mail]>
Signed-off-by: Jonathan Corbet <[e-mail]>

Documentation/trace/coresight.rst Documentation/trace/coresight/coresight.rst

···
     crw-------    1 root     root       10,  61 Jan  3 18:11 /dev/stm0
     root@genericarmv8:~#
 
-Details on how to use the generic STM API can be found here [#second]_.
+Details on how to use the generic STM API can be found here:- :doc:`../stm` [#second]_.
 
 .. [#first] Documentation/ABI/testing/sysfs-bus-coresight-devices-stm
 

Documentation/trace/coresight/index.rst

···
+==============================
+CoreSight - ARM Hardware Trace
+==============================
+
+.. toctree::
+   :maxdepth: 2
+   :glob:
+
+   *

Documentation/trace/index.rst

···
    intel_th
    stm
    sys-t
-   coresight
-   coresight-cpu-debug
+   coresight/index

MAINTAINERS

···
 L:	[e-mail] (moderated for non-subscribers)
 S:	Maintained
 F:	drivers/hwtracing/coresight/*
-F:	Documentation/trace/coresight.rst
-F:	Documentation/trace/coresight-cpu-debug.rst
+F:	Documentation/trace/coresight/*
 F:	Documentation/devicetree/bindings/arm/coresight.txt
 F:	Documentation/devicetree/bindings/arm/coresight-cpu-debug.txt
 F:	Documentation/ABI/testing/sysfs-bus-coresight-devices-*