Usage examples for logger (#15657)

* logger

* Update docs/source/main_classes/logging.mdx

Co-authored-by: Stas Bekman <stas00@users.noreply.github.com>

* Update docs/source/main_classes/logging.mdx

Co-authored-by: Stas Bekman <stas00@users.noreply.github.com>

Co-authored-by: Stas Bekman <stas00@users.noreply.github.com>

docs/source/main_classes/logging.mdx

@@ -36,11 +36,34 @@ Additionally, some `warnings` can be disabled by setting the environment variabl
 `TRANSFORMERS_NO_ADVISORY_WARNINGS` to a true value, like *1*. This will disable any warning that is logged using
 [`logger.warning_advice`]. For example:
 
-
 ```bash
 TRANSFORMERS_NO_ADVISORY_WARNINGS=1 ./myprogram.py
 ```
 
+Here is an example of how to use `logging` in a module:
+
+```python
+from transformers.utils import logging
+
+logging.set_verbosity_info()
+logger = logging.get_logger(__name__)
+logger.info("INFO")
+logger.warning("WARN")
+```
+
+Above, a `logger` instance is created from `logging.get_logger(__name__)`. If you want to use `logging` in a script, you shouldn't pass `__name__` to `logging.get_logger`. For example:
+
+```python
+from transformers.utils import logging
+
+if __name__ == "__main__":
+    logging.set_verbosity_info()
+    # leave it empy or use a string
+    logger = logging.get_logger()
+    logger.info("INFO")
+    logger.warning("WARN")
+```
+
 All the methods of this logging module are documented below, the main ones are
 [`logging.get_verbosity`] to get the current level of verbosity in the logger and
 [`logging.set_verbosity`] to set the verbosity to the level of your choice. In order (from the least