LCORE-200: Info about code style

CONTRIBUTING.md

@@ -153,3 +153,28 @@ To disable _Pylint_ rule in source code, the comment line in following format ca
 
 
 
+## Code style
+
+### Docstrings style
+We are using [Google's docstring style](https://google.github.io/styleguide/pyguide.html).
+
+Here is simple example:
+```python
+def function_with_pep484_type_annotations(param1: int, param2: str) -> bool:
+    """Example function with PEP 484 type annotations.
+
+    Args:
+        param1: The first parameter.
+        param2: The second parameter.
+
+    Returns:
+        The return value. True for success, False otherwise.
+
+    Raises:
+        ValueError: If the first parameter does not contain proper model name
+    """
+```
+
+For further guidance, see the rest of our codebase, or check sources online. There are many, eg. [this one](https://gist.github.com/redlotus/3bc387c2591e3e908c9b63b97b11d24e).
+
+