[py] document cygwin path for send_keys (#15275)

Author: Delta456

py/selenium/webdriver/remote/webelement.py

@@ -282,6 +282,8 @@ def send_keys(self, *value: str) -> None:
         >>> # Generally it's better to wrap the file path in one of the methods
         >>> # in os.path to return the actual path to support cross OS testing.
         >>> # file_input.send_keys(os.path.abspath("path/to/profilepic.gif"))
+        >>> # When using Cygwin, the path need to be provided in Windows format.
+        >>> # file_input.send_keys(f"C:/cygwin{os.path.abspath('path/to/profilepic.gif').replace('/', '\\')}")
         """
         # transfer file to another machine only if remote driver is used
         # the same behaviour as for java binding