Revise text of donate-thank-you page

Users who establish a recurring donation to Tor are delivered to this donate-thank-you page. I notice that one thing that this thank-you page does not say is "thank you", which seems like an oversight, so @smith and I wrote some new text for it, which is pasted below. Note two different header weights, and a couple links.

I usually assign tickets like this to @kez ; This is a lower priority than the Donate page backend

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H1: Thank you for standing up for the human right to privacy.

H2: Your support helps make Tor faster and more secure, and easier to use for the millions of people who need it.

Body: What's next? Get involved with Tor! Here's how to get started:

• Subscribe to the Tor newsletter https://newsletter.torproject.org/ to stay up to date on Tor news, releases, and events. One email a month. No ads. No tracking.
• Learn about volunteering to run a relay, write code, or spread the word about Tor. [link to community.torproject.org]

Thank you again for your support, and welcome to the Tor community.