Update about.md
Update about.md

fix link

Former-commit-id: a6817217f3c435d5e34b2ef4da837c1793f1f1cd [formerly aa8ffb88b4cba7662d7174cf0e3db6b08da26369]
Former-commit-id: 5d46cbc12d2b3319184398cd29c4fa18b54acff6
LibraryCarpentry/librarycarpentry.github.io,LibraryCarpentry/librarycarpentry.github.io,LibraryCarpentry/librarycarpentry.github.io