Update documentation to notify of the deprecation of Python 2.7 and 3.5

Author: sdispater

README.md

@@ -5,7 +5,10 @@ ensuring you have the right stack everywhere.
 
 ![Poetry Install](https://raw.githubusercontent.com/python-poetry/poetry/master/assets/install.gif)
 
-It supports Python 2.7 and 3.4+.
+It supports Python 2.7 and 3.5+.
+
+**Note**: Python 2.7 and 3.5 will no longer by supported in the next feature release (1.2).
+You should consider updating your Python version to a supported one.
 
 [![Tests Status](https://github.com/python-poetry/poetry/workflows/Tests/badge.svg?branch=master&event=push)](https://github.com/python-poetry/poetry/actions?query=workflow%3ATests+branch%3Amaster+event%3Apush)
 

docs/docs/index.md

@@ -6,9 +6,14 @@ It allows you to declare the libraries your project depends on and it will manag
 
 ## System requirements
 
-Poetry requires Python 2.7 or 3.4+. It is multi-platform and the goal is to make it work equally well
+Poetry requires Python 2.7 or 3.5+. It is multi-platform and the goal is to make it work equally well
 on Windows, Linux and OSX.
 
+!!! note
+
+    Python 2.7 and 3.5 will no longer by supported in the next feature release (1.2).
+    You should consider updating your Python version to a supported one.
+
 
 ## Installation