Merge pull request matplotlib#3933 from maxalbert/fix_typo_in_style_sheet_docs

Fix minor typo in docs: s/right/left/

Author: WeatherGod

doc/users/style_sheets.rst

@@ -61,7 +61,7 @@ a list of styles::
    >>> plt.style.use(['dark_background', 'presentation'])
 
 Note that styles further to the right will overwrite values that are already
-defined by styles on the right.
+defined by styles on the left.
 
 
 Temporary styling