Adding link for Angular Testing Succinctly (#9037)

* Adding link for Angular Testing Succinctly

* Updating link for Angular Testing Succinctly

* Update books/free-programming-books-langs.md

Co-authored-by: Sharan J <50091666+shrn01@users.noreply.github.com>

* Update books/free-programming-books-langs.md

Co-authored-by: Eric Hellman <eric@hellman.net>

Co-authored-by: Sharan J <50091666+shrn01@users.noreply.github.com>
Co-authored-by: Eric Hellman <eric@hellman.net>