Update index.md
Update index.md

change para head wording

Former-commit-id: 9624cc0cf89b31d0ce9e47b7ac9cb7d7493210c9 [formerly 453bc451e5743011575c50ea3ee8842d92c63815]
Former-commit-id: 3f11b6d7c8af780ad99dae2de7d8a3bcfd7d70fc
LibraryCarpentry/librarycarpentry.github.io,LibraryCarpentry/librarycarpentry.github.io,LibraryCarpentry/librarycarpentry.github.io