[docs] significant revamp - add sphinx support

make it possible to compile documentation via sphinx - main change is to
use RST instead of MarkDown for most files.

docs/FAQ.rst

@@ -0,0 +1,38 @@
+.. contents::
+
+FAQs
+====
+
+My bar doesn’t show any background colors
+-----------------------------------------
+
+Please check that you are using i3wm 4.12 or later. Before that, i3wm
+didn’t have background color support for the status bar.
+
+Some of the icons don’t render correctly
+----------------------------------------
+
+Please check that you have |Font Awesome| installed (version 4).
+
+.. note:: The |Font Awesome| is required for all themes that
+    contain icons (because that is the font that includes these icons).
+    Please refer to your distribution’s package management on how to install
+    them, or get them from their website directly. Also, please note that
+    Font Awesome removed some icons used by ``bumblebee-status`` from the
+    free set in version 5, so if possible, stick with 4.
+
+.. code-block:: bash
+
+   # Font Awesome installation instructions
+
+   # Arch Linux
+   $ sudo pacman -S awesome-terminal-fonts
+
+   # FreeBSD
+   $ sudo pkg install font-awesome
+   $ sudo pkg install py36-tzlocal py36-pytz py36-netifaces py36-psutil py36-requests #for dependencies
+
+   # Other
+   # see https://github.com/gabrielelana/awesome-terminal-fonts
+
+.. |Font Awesome| image:: https://fontawesome.com/