Updating Participant Schedule link index.html.md

Why is this change being made?

The link to Participant schedule in the quick reference guide is broken. Hence updating for the correct link

Does this MR meet the acceptance criteria?

Assign to DRI

• Did you assign this change to the correct DRI of the page or information you are changing?

Conformity

• Added description to this MR explaining the reasons for the proposed change, per say-why-not-just-what