[V3 Docs] Add install guides to the documentation (#1005)

* [Docs] add install guides to the documentation

* formatting changes

docs/install_windows.rst

@@ -0,0 +1,37 @@
+.. windows installation docs
+
+=========================
+Installing Red on Windows
+=========================
+
+---------------
+Needed Software
+---------------
+
+* `Python <https://python.org/downloads/>`_ - Red needs at least Python 3.5
+
+.. attention:: Please note that 3.6 has issues on some versions of Windows.
+               If you try using Red with 3.6 and experience issues, uninstall
+               Python 3.6 and install the latest version of Python 3.5
+
+.. note:: Please make sure that the box to add Python to PATH is CHECKED, otherwise
+          you may run into issues when trying to run Red
+
+* `Git <https://git-scm.com/download/win>`_
+
+.. attention:: Please choose the option to "Run Git from the Windows Command Prompt" in Git's setup
+
+--------------
+Installing Red
+--------------
+
+1. Open a command prompt (open Start, search for "command prompt", then click it)
+2. Run the appropriate command, depending on if you want audio or not
+  * No audio: :code:`python -m pip install Red-DiscordBot`
+  * Audio: :code:`python -m pip install Red-DiscordBot[voice]`
+3. Once that has completed, run :code:`redbot-setup` to set up your instance
+  * This will set the location where data will be stored, as well as your
+    storage backend and the name of the instance (which will be used for
+    running the bot)
+4. Once done setting up the instance, run :code:`redbot <your instance name>` to run Red.
+   It will walk through the initial setup, asking for your token and a prefix