Update extraction for Elsevier

[Yinghao Li]

Extractor fails to extract content from https://www.sciencedirect.com/science/article/pii/S1572665719301237?via%3Dihub.

The issue likely appears at

ChemistryHTMLPaperParser/chempp/section_extr.py

Line 440 in c46f025

 if record_data or 'sec' in sec_id: 

Adding condition and sec_id.startswith('s') might solve the issue.