Fix failing rtd document generation and smuggle some typo corrections.

[slaff]

No description provided.

[what-the-diff]

PR Summary

• Operating System Updated for Readthedocs
  The operating system version for building our project documentation on 'ReadtheDocs' has been updated to Ubuntu 20.04. This will ensure that our documentation is built in a stable and updated environment.

• Typo Corrections in Documentation
  Minor typo errors in the documentation files, specifically in 'command-handler.rst', 'events.rst', and 'example.output.txt' have been corrected. These changes improve readability and accuracy of our documentation.