add security writeups and dev tools link

[computerality]

trafficstars

[dguido]

Looks good, add an entry to the Table of Contents. Maybe there are a few other historical writeups that everyone should be familiar with. Maybe an old Hacking Distributed writeup on the DAO hack and similar stuff?

[computerality]

Added toc. There are definitely other good ones but I don't have links handy. Can do them in a later commit.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}