docs: add sample for TC400 (logging.exception)

docs/violations/README.md

@@ -32,3 +32,10 @@
 | ----------------- | --------------------------------- |
 | [TC300](TC300.md) | Consider adding an `else` block   |
 | [TC301](TC301.md) | Avoid direct raises in `try` body |
+
+## `TC4xx` - Logging usage
+
+
+| Code              | Description                                 |
+| ----------------- | ------------------------------------------- |
+| [TC400](TC400.md) | Use logging '.exception' instead of 'error' |

docs/violations/TC400.md

@@ -0,0 +1,29 @@
+# `TC400` - Use logging '.exception' instead of 'error'
+
+## Why is it bad
+
+[Python docs](https://docs.python.org/3/library/logging.html#logging.Logger.exception) point out that you should use `exception` method inside an exception handler. It automatically add the stack trace and logs the message as `ERROR` level.
+
+## How it looks like
+
+```py
+def main_function():
+    try:
+        process()
+        handle()
+        finish()
+    except Exception as ex:
+        logger.error("Context message here")
+```
+
+## How it should be
+
+```py
+def main_function():
+    try:
+        process()
+        handle()
+        finish()
+    except Exception:
+        logger.exception("Context message here")
+```

src/tests/samples/violations/log_error.py

@@ -0,0 +1,10 @@
+import logging
+
+logger = logging.getLogger(__name__)
+
+
+def func():
+    try:
+        a = 1
+    except Exception:
+        logger.error("I'm using 'error', but should be using 'exception'")