Remove Vocascan (unmaintained since June 2022, website down/self-signed cert) (#3896)

- ref. https://github.com/awesome-selfhosted/awesome-selfhosted/issues/3558
- WARNING:awesome_lint.py: Vocascan: last updated -366 days, 23:22:41.637302 ago, older than 365 days
- https://vocascan.com/ : HTTPSConnectionPool(host='vocascan.com', port=443): Max retries exceeded with url: / (Caused by SSLError(SSLCertVerificationError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: self-signed certificate (_ssl.c:997)')))

README.md

@@ -1176,7 +1176,6 @@ Tools and software to help with education and learning.
 - [OpenOLAT](https://www.openolat.com/?lang=en) - OpenOLAT is a web-based learning management system for teaching, education, assessment and communication. ([Demo](https://learn.olat.com), [Source Code](https://github.com/OpenOLAT/OpenOLAT)) `Apache-2.0` `Java`
 - [RELATE](https://documen.tician.de/relate/) - RELATE is a web-based courseware package, includes features such as: flexible rules, statistics, multi-course support, class calendar. ([Source Code](https://github.com/inducer/relate)) `MIT` `Python`
 - [RosarioSIS](https://www.rosariosis.org/) - RosarioSIS, free Student Information System for school management. ([Demo](https://www.rosariosis.org/demo/), [Source Code](https://gitlab.com/francoisjacquet/rosariosis/)) `GPL-2.0` `PHP`
-- [Vocascan](https://vocascan.com/) - A highly configurable vocabulary trainer. ([Source Code](https://github.com/vocascan/vocascan-server), [Clients](https://github.com/vocascan/vocascan-desktop)) `Apache-2.0` `Nodejs`
 
 
 ### Maps and Global Positioning System (GPS)