Broken link to flash card challenge in tutorial

[tripokey]

The link to the flash card challenge under "Starting Your Project" is: http://wiki.openhatch.org/Flash_card_challenge

And it should be: https://wiki.openhatch.org/wiki/Flash_card_challenge

[vitiral]

Thanks for the bug. I'm going to hopefully be doing a full docs refactor soon and this will be involved in that.