Exclude '_venv' directory

Author: ruslo

docs/conf.py

@@ -82,7 +82,7 @@
 
 # List of patterns, relative to source directory, that match files and
 # directories to ignore when looking for source files.
-exclude_patterns = ['_build', 'rtfd-css']
+exclude_patterns = ['_build', '_venv', 'rtfd-css']
 
 # The reST default role (used for this markup: `text`) to use for all
 # documents.