Upgrade architecture + 5.0 Bot API (#469)

Upgrade architecture + 5.0 Bot API (#469)
* Moved `methods`, `types` and `client` to root package
* Removed update handler from routers to dispatcher
* Reworked events propagation mechanism to handlers
* Reworked inner middlewares logic (very small change)
* Updated to Bot API 5.0
* Initial migration from MkDocs to Sphinx + config for readthedocs

docs2/install.rst

@@ -0,0 +1,64 @@
+############
+Installation
+############
+
+Stable (2.x)
+============
+
+Using PIP
+---------
+
+.. code-block:: bash
+
+    pip install -U aiogram
+
+
+Using poetry
+------------
+
+.. code-block:: bash
+
+    poetry add aiogram
+
+
+Using Pipenv
+------------
+
+.. code-block:: bash
+
+    pipenv install aiogram
+
+Using poetry
+------------
+
+.. code-block:: bash
+
+    poetry add aiogram
+
+Using Pacman
+------------
+*aiogram* is also available in Arch Linux Repository, so you can install this framework on any
+Arch-based distribution like Arch Linux, Antergos, Manjaro, etc. To do this, just use pacman
+to install the `python-aiogram <https://archlinux.org/packages/community/any/python-aiogram/>`_ package:
+
+.. code-block:: bash
+
+    pacman -S python-aiogram
+
+Development build (3.x)
+=======================
+
+From private PyPi index
+-----------------------
+
+On every push to the `dev-3.x` branch GitHub Actions build the package and publish
+to the `2038.host <https://aiogram.2038.io/simple>`_ server with seems like official PyPi files structure.
+That's mean you can always install latest (may be unstable) build via next command:
+
+.. code-block:: bash
+
+    pip install --extra-index-url https://dev-docs.aiogram.dev/simple --pre aiogram
+
+
+In this repository available only last success build. All previous builds is always removes
+before uploading new one. Also before building this package all tests is also pass.