Add a maintainer entry profile for documentation

Documentation should lead by example, so here's a basic maintainer entry
profile for this subsystem.
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/doc-guide/index.rst

@@ -11,6 +11,7 @@ How to write kernel documentation
    kernel-doc
    parse-headers
    contributing
+   maintainer-profile
 
 .. only::  subproject and html
 

Documentation/doc-guide/maintainer-profile.rst

+.. SPDX-License-Identifier: GPL-2.0
+Documentation subsystem maintainer entry profile
+================================================
+
+The documentation "subsystem" is the central coordinating point for the
+kernel's documentation and associated infrastructure.  It covers the
+hierarchy under Documentation/ (with the exception of
+Documentation/device-tree), various utilities under scripts/ and, at least
+some of the time, LICENSES/.
+
+It's worth noting, though, that the boundaries of this subsystem are rather
+fuzzier than normal.  Many other subsystem maintainers like to keep control
+of portions of Documentation/, and many more freely apply changes there
+when it is convenient.  Beyond that, much of the kernel's documentation is
+found in the source as kerneldoc comments; those are usually (but not
+always) maintained by the relevant subsystem maintainer.
+
+The mailing list for documentation is linux-doc@vger.kernel.org.  Patches
+should be made against the docs-next tree whenever possible.
+
+Submit checklist addendum
+-------------------------
+
+When making documentation changes, you should actually build the
+documentation and ensure that no new errors or warnings have been
+introduced.  Generating HTML documents and looking at the result will help
+to avoid unsightly misunderstandings about how things will be rendered.
+
+Key cycle dates
+---------------
+
+Patches can be sent anytime, but response will be slower than usual during
+the merge window.  The docs tree tends to close late before the merge
+window opens, since the risk of regressions from documentation patches is
+low.
+
+Review cadence
+--------------
+
+I am the sole maintainer for the documentation subsystem, and I am doing
+the work on my own time, so the response to patches will occasionally be
+slow.  I try to always send out a notification when a patch is merged (or
+when I decide that one cannot be).  Do not hesitate to send a ping if you
+have not heard back within a week of sending a patch.

Documentation/maintainer/maintainer-entry-profile.rst

@@ -99,4 +99,5 @@ to do something different in the near future.
 .. toctree::
    :maxdepth: 1
 
+   ../doc-guide/maintainer-profile
    ../nvdimm/maintainer-entry-profile