Update about.md
Update about.md

fix errors

Former-commit-id: c4ed4087cc3f0ae0b5531762a04b1ef4d3febe81 [formerly 87b5c01769f9eb27231acc260e1b5e10b6490252]
Former-commit-id: 13a1c31cca2281e4fd18a17d007081750dec8493
LibraryCarpentry/librarycarpentry.github.io,LibraryCarpentry/librarycarpentry.github.io,LibraryCarpentry/librarycarpentry.github.io