docs: add event calendar in community page (#3767)

website/community/index.mdx

@@ -40,6 +40,14 @@ If you email us with a code snippet, make sure that:
 * you keep formatting when pasting code to keep the code readable
 * there are enough import statements to avoid ambiguities
 
+## Upcoming Community Events
+
+We have a calendar that tracks all our upcoming events like community sync.
+
+<iframe src="https://calendar.google.com/calendar/embed?src=d32a8b1c08fc40d4230e3ce89145fd0e9a1ea4a374893a23ec7bd28ca646db45%40group.calendar.google.com&ctz=Asia%2FShanghai" style={{border: 0, width: "100%", maxWidth: "600px", height: "600px", aspectRatio: 1}} frameBorder="0"></iframe>
+
+If prefer to add these events to your personal calendar, please use this iCal link: [Add to your calendar](https://calendar.google.com/calendar/ical/d32a8b1c08fc40d4230e3ce89145fd0e9a1ea4a374893a23ec7bd28ca646db45%40group.calendar.google.com/public/basic.ics)
+
 ## Issue tracker
 
 We use GitHub Issues to track all code related issues: https://github.com/apache/incubator-opendal/issues