Merge pull request public-apis#6075 from prantikmedhi/fix/openmercantil-api

docs: add OpenMercantil API

Author: ArindamOSS

README.md

@@ -1166,6 +1166,7 @@ API | Description | Auth | HTTPS | CORS |
 | [Open Government, USA](https://www.data.gov/) | United States Government Open Data | No | Yes | Unknown |
 | [Open Government, Victoria State Government](https://www.data.vic.gov.au/) | Victoria State Government Open Data | No | Yes | Unknown |
 | [Open Government, West Australia](https://data.wa.gov.au/) | West Australia Open Data | No | Yes | Unknown |
+| [OpenMercantil](https://openmercantil.es/api/documentacion) | Spanish company public data and BORME event timelines | No | Yes | Yes |
 | [OpenRegistry](https://openregistry.sophymarine.com) | Real-time queries to 27 national company registries (UK, FR, DE, IT, ES, KR + 21 more) | `OAuth` | Yes | Unknown |
 | [PRC Exam Schedule](https://api.whenisthenextboardexam.com/docs/) | Unofficial Philippine Professional Regulation Commission's examination schedule | No | Yes | Yes |
 | [Represent by Open North](https://represent.opennorth.ca/) | Find Canadian Government Representatives | No | Yes | Unknown |