enable nitpicky warnings for docs builds

docs/conf.py

@@ -103,6 +103,17 @@ pygments_style = "sphinx"
 # If true, `todo` and `todoList` produce output, else they produce nothing.
 todo_include_todos = False
 
+# If true, Sphinx will warn about all references where the target cannot be found.
+# Default is False. You can activate this mode temporarily using the -n command-line
+# switch.
+nitpicky = True
+
+# A list of (type, target) tuples (by default empty) that should be ignored when
+# generating warnings in “nitpicky mode”. Note that type should include the domain name
+# if present. Example entries would be ('py:func', 'int') or
+# ('envvar', 'LD_LIBRARY_PATH').
+# nitpick_ignore = []
+
 
 # -- Options for HTML output ----------------------------------------------