docs: Fix formatting of allow_single_file_parallelism

[nuno-faria]

Which issue does this PR close?

• N/A.

Rationale for this change

The doc for allow_single_file_parallelism is not correctly escaped.

What changes are included in this PR?

• Escape *.

What is the testing strategy for this PR?

Are there any user-facing changes?

No.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.41%. Comparing base (99af44a) to head (4d2af0d).

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #25551      +/-   ##
==========================================
- Coverage   82.41%   82.41%   -0.01%     
==========================================
  Files        1138     1138              
  Lines      435299   435299              
  Branches   435299   435299              
==========================================
- Hits       358749   358742       -7     
- Misses      54840    54845       +5     
- Partials    21710    21712       +2     

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