Update docs/tutorial/contribution-page.md
Update docs/tutorial/contribution-page.md

Ah yes! Thanks for that.

Co-authored-by: Rich Lott <dc9c87543f019c3caa79085ee5e93ce4d378b2f6@users.noreply.github.com>
artfulrobot/uk.artfulrobot.civicrm.gocardless,artfulrobot/uk.artfulrobot.civicrm.gocardless