Add contributors list as seprate file

CONTRIB.rst

+.. _contributors:
+
+Contributors
+#############
+
+This is a list of people who have made contributions to BeagleBoard.org unified documentation project.
+
+People are listed alphabetically, as verified with Unix sort:
+
+.. code-block:: shell
+
+    $ grep "^- " CONTRIB.rst | LC_ALL=C sort -u -c -f
+
+
+This is certainly not comprehensive, and if you've been overlooked (sorry!), please open an issue on GitLab or mention it on the forum.
+
+- `Andrei Aldea <https://git.beagleboard.org/andrei1998>`_
+- `Ayush Singh <https://git.beagleboard.org/ayush1325>`_
+- Cathy Wicks
+- `Deepak Khatri <https://git.beagleboard.org/lorforlinux>`_
+- `Dhruva Gole <https://git.beagleboard.org/dhruvag2000>`_
+- `Harshil Bhatt <https://git.beagleboard.org/harshilbhatt2001>`_
+- `Jason Kridner <https://git.beagleboard.org/jkridner/>`_
+- `Jian De <https://git.beagleboard.org/jiande>`_
+- `Joshua Neal <https://git.beagleboard.org/jdneal>`_
+- `Kai Yamada <https://git.beagleboard.org/gpioblink>`_
+- `Krishna Narayanan <https://git.beagleboard.org/Krishna_13>`_
+- `Mark A. Yoder <https://git.beagleboard.org/yoder>`_
+- `Robert Nelson <https://git.beagleboard.org/RobertCNelson>`_
+- `Sabeeh Khan <https://git.beagleboard.org/sabeeh.khan14>`_
+- `Seth N <https://git.beagleboard.org/silver2row>`_
\ No newline at end of file