[docs] Include link to Iceberg Dev Events in docs (apache#2253)

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Closes apache#2238 

# Rationale for this change
The pyiceberg monthly sync is now a part of the Iceberg Dev Events
calendar.

# Are these changes tested?
Just docs

# Are there any user-facing changes?

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Author: rambleraptor

mkdocs/docs/community.md

@@ -30,7 +30,7 @@ Community discussions happen primarily on the [dev mailing list](https://lists.a
 
 ## Iceberg Community Events
 
-The PyIceberg community sync is on the last Tuesday of every month. To join, make sure to subscribe to the [iceberg-python-sync Google group](https://groups.google.com/g/iceberg-python-sync).
+The PyIceberg community sync is on the last Tuesday of every month. The calendar event is located on the [Iceberg Dev Events](https://iceberg.apache.org/community#iceberg-community-events) calendar.
 
 ## Community Guidelines