README: Outdated “information about PCRE2” link to Regular-Expressions.info in API Overview

[Chealer]

The API Overview section of the README contains:

For third-party documentation, see further:
[…]

• Jan Goyvaerts' popular Regular-Expressions.info site includes information about PCRE2 as well as tutorials and highly detailed comparisons of PCRE2 to other regular expression dialects.

This actually links to a page about PCRE 1, and only indirectly to Regular-Expressions.info’s page about PCRE 2.

By the way

I recommend changing:

For third-party documentation, see further:

…to:

For further information, third-party documentation is available:

🅭🄍