[DOC] Give more details about dbx.get_last_modified_file()

[copdips]

Expected Behavior

Get more examples or use cases where we need to use dbx.get_last_modified_file(): https://dbx.readthedocs.io/en/latest/features/jinja_support/#built-in-functions

Current Behavior

Can not figure out what does it mean with current doc:

returns path to the last modified file from a path with a given extension.
Path should be provided as a string, extension should be provided without a dot, e.g. jar.

Steps to Reproduce (for bugs)

Context

Your Environment

• dbx version used:
• Databricks Runtime version: