Add project from Toronto Hub 2023 to website

[sunclara]

trafficstars

Changes proposed in this pull request:

• Add project titled "fMRI_ADHD_connectivity" to the Brainhack school website
• Almost all commits are edits to the "index.md" file in the "fMRI_ADHD_connectivity" project folder
• All other commits are image uploads
• Please find the index.md file at this path: sunclara/brainhack_project_page/content/en/project/fMRI_ADHD_connectivity/index.md

[sunclara]

Hello Toronto TAs @juchiyu, sorry I'm not sure how to assign you to be a "reviewer" but I wanted to notify you that we submitted a pull request. @complexbrains

[lunebellec]

Sorry this took so long, merging.