add link to intro talk

Author: CPernet

PETBIDS-Onboarding2025/README.md

@@ -79,7 +79,7 @@ This list may grow, but at present, we plan to provide hands-on training in the
 | Time   | Presenters         | Topic                                                           |
 |--------|--------------------|-----------------------------------------------------------------|
 | 09h30  | ☕                 | COFFEE, TEA & SNACKS                                            |
-| 10h00  | Cyril Pernet       | Introduction to BIDS                                            |
+| 10h00  | Cyril Pernet       | [Introduction to BIDS](https://docs.google.com/presentation/d/1pIXA1I3y3MmbTSDKLYkwnTbK-tve9rHP/edit?usp=sharing&ouid=105032844288633808506&rtpof=true&sd=true)                                       |
 | 11h00  | Martin Nørgaard    | BIDS Apps and Analysis Workflows                                |
 | 12h00  | 🧆                 | LUNCH                                                           |
 | 13h00  | Cyril Pernet       | EU landscape for sharing brain imaging data                     |