docs: add sample for TC401 (logging w/o object)

docs/violations/README.md

@@ -36,6 +36,7 @@
 ## `TC4xx` - Logging usage
 
 
-| Code              | Description                                 |
-| ----------------- | ------------------------------------------- |
-| [TC400](TC400.md) | Use logging '.exception' instead of 'error' |
+| Code              | Description                                  |
+| ----------------- | -------------------------------------------- |
+| [TC400](TC400.md) | Use logging `.exception` instead of `.error` |
+| [TC401](TC401.md) | Do not log the exception object              |

docs/violations/TC401.md

@@ -0,0 +1,29 @@
+# `TC401` - Do not log the exception object
+
+## Why is it bad
+
+It's verbose, by using `logging.exception` you're already getting the exception message. Use the message to give context instead.
+
+## How it looks like
+
+```py
+def main_function():
+    try:
+        process()
+        handle()
+        finish()
+    except Exception as ex:
+        logger.exception(f"Found an error: {ex}")  # 'ex' message is going to be displayed twice
+```
+
+## How it should be
+
+```py
+def main_function():
+    try:
+        process()
+        handle()
+        finish()
+    except Exception:  # <- No need to get object
+        logger.exception("Something failed during main_function")  # <- Message will be shown alongside stack trace
+```