Update Python CHANGES doc

For both 3.1 and 3.2

Author: shs96c

py/CHANGES

@@ -1,3 +1,12 @@
+Selenium 3.2.0
+* No major changes to Python bindings
+
+Selenium 3.1.0
+* Fix python HTTPS encoding for python driver (#3379)
+* Allow Firefox preferences to be set directly in Options
+* Fix shutdown and process termination (#3263)
+* Preventing exception if log_path is none or empty. Fixes #3128
+
 Selenium 3.0.2
 * Add support for W3C Get Active Element
 * Return when we use executeScript for faking WebElement.get_property