Add Discord link to README

Added a Discord link for community engagement.

Author: eddietejeda

README.md

@@ -4,6 +4,8 @@ A [DataFusion](https://datafusion.apache.org/) extension for querying [DuckLake]
 
 The goal of this project is to make DuckLake a first-class, Arrow-native lakehouse format inside DataFusion.
 
+[Join the Discord](https://discord.gg/FefVb3u9sH)
+
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 ## Currently Supported