fix: support generating submission for mdoc

[TimoGlastra]

small issue found while integrating into oid4vp. It needed this mapping to allow generating the submission for mdocs as well

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.80%. Comparing base (24e93ea) to head (21b664b).
Report is 3 commits behind head on feature/mdoc-parsing.

Additional details and impacted files

@@                  Coverage Diff                  @@
##           feature/mdoc-parsing     #184   +/-   ##
=====================================================
  Coverage                 92.80%   92.80%           
=====================================================
  Files                        66       66           
  Lines                      2739     2739           
  Branches                    719      648   -71     
=====================================================
  Hits                       2542     2542           
- Misses                      192      196    +4     
+ Partials                      5        1    -4     

Flag	Coverage Δ
unittest	92.80% <ø> (ø)

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