Update README to state that Python 3 is also supported.

Author: xuhdev

README.md

@@ -7,12 +7,13 @@ This is an [EditorConfig][] plugin for Vim. This plugin could be found on both
 
 ## Installation
 
-If your Vim is not compiled with `+python` feature (You can verify if the
-`+python` feature is included by running `:ver`.  Most Linux distributions and
-with the official Windows binary have the `+python` feature enabled), please
-first download the [EditorConfig core][] and follow the instructions in the
-README and INSTALL files to install it. This plugin would NOT work if neither
-`+python` nor EditorConfig core is available.
+If your Vim is not compiled with `+python` or `+python3` feature (You can verify
+if the `+python` or `+python3` feature is included by running `:ver`. Most Linux
+distributions and with the official Windows binary have the `+python` and
+`+python3` feature enabled), please first download the [EditorConfig core][] and
+follow the instructions in the README and INSTALL files to install it. This
+plugin would NOT work if neither `+python`/`+python3` nor EditorConfig core is
+available.
 
 To install this plugin, you can use one of the following ways: