about: fix NLnet project link

It was missing the '/project' directory.

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

about.md

@@ -17,7 +17,7 @@ Mastodon:
 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).
+more at the [NLnet project page](https://nlnet.nl/project/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)