docs: cpu-freq: convert index.txt to ReST

most of the stuff there can be re-used with ReST format,
but we need to add an empty TOC and remove the existing
entries, as the following conversion patches will be re-adding
them, as they're converted.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Documentation/cpu-freq/index.rst

@@ -0,0 +1,35 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==============================================================================
+Linux CPUFreq - CPU frequency and voltage scaling code in the Linux(TM) kernel
+==============================================================================
+
+Author: Dominik Brodowski  <linux@brodo.de>
+
+   Clock scaling allows you to change the clock speed of the CPUs on the
+   fly. This is a nice method to save battery power, because the lower
+   the clock speed, the less power the CPU consumes.
+
+
+.. toctree::
+   :maxdepth: 1
+
+Mailing List
+------------
+There is a CPU frequency changing CVS commit and general list where
+you can report bugs, problems or submit patches. To post a message,
+send an email to linux-pm@vger.kernel.org.
+
+Links
+-----
+the FTP archives:
+* ftp://ftp.linux.org.uk/pub/linux/cpufreq/
+
+how to access the CVS repository:
+* http://cvs.arm.linux.org.uk/
+
+the CPUFreq Mailing list:
+* http://vger.kernel.org/vger-lists.html#linux-pm
+
+Clock and voltage scaling for the SA-1100:
+* http://www.lartmaker.nl/projects/scaling