doc: unpack result to access TracerouteResult

[isidroas]

Fixes:

>>> a.world_trace()
AttributeError: 'tuple' object has no attribute 'world_trace'

Checklist:

• If you are new to Scapy: I have checked CONTRIBUTING.md (esp. section submitting-pull-requests)
• I squashed commits belonging together
• I added unit tests or explained why they are not relevant
• I executed the regression tests (using cd test && ./run_tests or tox)
• If the PR is still not finished, please create a Draft Pull Request

[gpotter2]

Thanks for the PR !

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.16%. Comparing base (56de4f4) to head (c66cb56).
Report is 6 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4763   +/-   ##
=======================================
  Coverage   82.16%   82.16%           
=======================================
  Files         362      362           
  Lines       87359    87359           
=======================================
  Hits        71777    71777           
  Misses      15582    15582           

see 4 files with indirect coverage changes

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