about: add funding section

Because it is good to mention that with the logo somewhere.

Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>

about.md

@@ -11,3 +11,13 @@ permalink: /about/
 Mastodon:
 - [Matt](https://fosstodon.org/@matttbe)
 - [MPTCP](https://social.kernel.org/mptcp)
+
+## Funding
+
+This project is funded through [NGI0 Core](https://nlnet.nl/core), a fund
+established by [NLnet](https://nlnet.nl) with financial support from the
+European Commission's [Next Generation Internet](https://ngi.eu) program. Learn
+more at the [NLnet project page](https://nlnet.nl/MPTCP-deployability).
+
+[<img src="https://nlnet.nl/logo/banner.png" alt="NLnet foundation logo" width="20%" />](https://nlnet.nl)
+[<img src="https://nlnet.nl/image/logos/NGI0_tag.svg" alt="NGI Zero Logo" width="20%" />](https://nlnet.nl/core)