Fix "hardware random number generator" link at bottom of "Digital software security" section

[basnappl]

Consider updating _docs/extend/security.md, because ...

The "hardware random number generator" link at bottom of "Digital software security" section doesn't land on a helpful Wikipedia page. Maybe it should point to:

https://en.wikipedia.org/wiki/Hardware_random_number_generator

?

[bitcoinhodler]

Thank you for the report.

This project is abandoned by its maintainers. The document is in poor shape, and has been for years.