Improve Code Documentation/Comments

[ecwood]

I am starting this issue to be a running list of files that need to be better documented (particularly through comments). While some of the code is well commented, that is not the case for all of the files. This list will also include code that needs to be refactored. This work will take place on the jsonlines branch.

• [x] report_stats_on_json_kg.py
• [ ] smpdb_csv_to_kg_json.py
• [ ] chembl_mysql_to_kg_json.py
• [x] query_kegg.py