Fix section collection

[natygyoon]

Problem:
Not all sections were collected into elements.

How to replicate this issue:
Run the following commands which test this document.

• PYTHONPATH=. pytest "test_real_docs/test_real_example\ s.py::test_first_last[bj-SECSection.CERTAIN_TRADEMARKS-first]"
• PYTHONPATH=. pytest "test_real_docs/test_real_example\ s.py::test_first_last[bj-SECSection.CERTAIN_TRADEMARKS-last]"

Note that the NarrativeText part of "CERTAIN_TRADEMARKS" section was not collected into elements in the first place.

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