scheduler.py: Correct some anomalies within the docstrings

Qinustyrequested to merge
Qinusty/scheduler_docstring_fix into master

Description

Update some docstrings throughout scheduler.py to correct return types and typos.

Changes proposed in this merge request:

  • Correct return types of elapsed_time() and run() to return timedelta instead of datetime.
  • Correct typo in Scheduler class docstring.
Edited by Qinusty

Merge request reports