1. There is no public Bitcoin address associated with Wikipedia.
2. The amount donated is denominated in USD (thus I cannot specify the exact amount of the pledge).
3. There isn't that much by way of confirmation of the donation - all I get is a Coinbase receipt like https://coinbase.com/orders/c2e107a91057283dcebf7708255650c3/receipt.
Per the rules of the titular pledge, I am now to forward the 8.0728757 pledged bitcoins to Wikipedia. But given the above it's not clear to me how to do that in a way that proves that I have.
I welcome suggestions for the best way to do it.
(PS I believe there was little to no affect of this pledge on their decision, but the money is going to a good cause anyway).
Linking to the receipt provided by Coinbase and the transaction on Blockchain.info would be adequate in my opinion. This would verify that the bitcoins were sent when they were worth the amount in USD as stated on the Coinbase receipt. While this may not specifically prove that the bitcoins came from you, it would be unlikely that you waited to send the 8.0728757 BTC until someone else happened to send that exact amount and were able to access their online receipt.
Disclosure: I don't recall sending a donation to this so I have no stake in the outcome.