Broken links in documentation.

[Propfend]

On the chapter about Bump allocation, we have two broken links:

https://fitzgeraldnick.com/2019/11/01/always-bump-downwards.html

and

http://www.cs.utexas.edu/users/speedway/DaCapo/papers/immix-pldi-2008.pdf

those are link 1 and [2]. See line.

[pliniker]

Thank you for reporting this, I'll address it.