Fix a dead ReDoS link in docs

[geoffw0]

Fix a dead link related to the ReDoS query in all places where it occurs.

• old link: http://www.cs.bham.ac.uk/~hxt/research/reg-exp-sec.pdf (claimed to be "James Kirrage, Asiri Rathnayake, Hayo Thielecke: Static Analysis for Regular Expression Denial-of-Service Attacks. NSS 2013.", now "404: Not Found")
• new link: https://arxiv.org/abs/1301.0849 ("Static Analysis for Regular Expression Denial-of-Service Attacks James Kirrage, Asiri Rathnayake, Hayo Thielecke")
• I noticed this was a dead link while working on the Swift ReDoS query .qhelp, and already did the substitution there. This PR extends that substitution to every other occurrence.

[github-actions]

QHelp previews:

[subatoi]

Thank you!

[geoffw0]

If there are no objections I'm going to merge this at the end of my day today whether or not it's been approved by all teams. There are several approvals already and I don't think it's a particularly controversial change.

[geoffw0]

Merging...