DOCS: Minor updates to handoffs.ipynb

[xtophs]

Updates:

• added missing backtick for formatting class name
• typo in user response example

Why are these changes needed?

Fixing minor doc issues

Related issue number

N/A

Checks

• [ X] I've included any doc changes needed for https://microsoft.github.io/autogen/. See https://github.com/microsoft/autogen/blob/main/CONTRIBUTING.md to build and test documentation locally.
• [ X] I've added tests (if relevant) corresponding to the changes introduced in this PR.
• [ X] I've made sure all auto checks have passed.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 75.63%. Comparing base (95585b4) to head (747c01e).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5665   +/-   ##
=======================================
  Coverage   75.63%   75.63%           
=======================================
  Files         171      171           
  Lines       10548    10548           
=======================================
  Hits         7978     7978           
  Misses       2570     2570           

Flag	Coverage Δ
unittests	75.63% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.