fix typo in readme

README.md

@@ -126,7 +126,7 @@ reading it from the following sources, in this order:
    Python. (In other words, whatever version would run if pyenv weren't in your
    `PATH`.)
 
-**NOTE:** You can activate multiple versions at the same time, including mulitple
+**NOTE:** You can activate multiple versions at the same time, including multiple
 versions of Python2 or Python3 simultaneously. This allows for parallel usage of
 Python2 and Python3, and is required with tools like `tox`. For example, to set
 your path to first use your `system` Python and Python3 (set to 2.7.9 and 3.4.2