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/api/methods/send_document.rst

@@ -0,0 +1,51 @@
+############
+sendDocument
+############
+
+Returns: :obj:`Message`
+
+.. automodule:: aiogram.methods.send_document
+    :members:
+    :member-order: bysource
+    :undoc-members: True
+
+
+Usage
+=====
+
+As bot method
+-------------
+
+.. code-block::
+
+    result: Message = await bot.send_document(...)
+
+
+Method as object
+----------------
+
+Imports:
+
+- :code:`from aiogram.methods.send_document import SendDocument`
+- alias: :code:`from aiogram.methods import SendDocument`
+
+In handlers with current bot
+----------------------------
+
+.. code-block:: python
+
+    result: Message = await SendDocument(...)
+
+With specific bot
+~~~~~~~~~~~~~~~~~
+
+.. code-block:: python
+
+    result: Message = await bot(SendDocument(...))
+
+As reply into Webhook in handler
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. code-block:: python
+
+    return SendDocument(...)