Exclude .venv directory from sphinx

cpp/docs/conf.py

@@ -91,7 +91,7 @@ language = 'en'
 # List of patterns, relative to source directory, that match files and
 # directories to ignore when looking for source files.
 # This patterns also effect to html_static_path and html_extra_path
-exclude_patterns = []
+exclude_patterns = ['.venv/**']
 
 # The reST default role (used for this markup: `text`) to use for all
 # documents.