Removed _static file from list of html_static_paths as we dont use it…

… currently and it throws sphinx warnings.

docs/source/conf.py

@@ -107,7 +107,7 @@
 # Add any paths that contain custom static files (such as style sheets) here,
 # relative to this directory. They are copied after the builtin static files,
 # so a file named "default.css" will overwrite the builtin "default.css".
-html_static_path = ['_static']
+html_static_path = []
 html_theme_path = [stsci_rtd_theme.get_html_theme_path()]
 
 # Custom sidebar templates, must be a dictionary that maps document names