landing: add gbcompo25 teaser box

Author: avivace

website/README.md

@@ -66,6 +66,10 @@ We are a non for profit collective of passionate developers and hackers working
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+::: important GB Compo 2025
+The biggest Game Boy coding jam is back! Create Game Boy games and compete for the glory (and great prizes). [Join the Game Boy Competition 2025 now](https://itch.io/jam/gbcompo25).
+:::
+
 # Projects
 
 Here's what we are up to:<br>