docs: include disclaimer in announcement template (#3172)

website/docs/contributing/release.md

@@ -540,6 +540,18 @@ OpenDAL Resources:
 
 Thanks
 On behalf of Apache OpenDAL community
+
+---
+Apache OpenDAL (incubating) is an effort undergoing incubation at the Apache
+Software Foundation (ASF), sponsored by the Apache Incubator PMC.
+
+Incubation is required of all newly accepted projects until a further review
+indicates that the infrastructure, communications, and decision making process
+have stabilized in a manner consistent with other successful ASF projects.
+
+While incubation status is not necessarily a reflection of the completeness
+or stability of the code, it does indicate that the project has yet to be
+fully endorsed by the ASF.
 ```
 
 Example: <https://lists.apache.org/thread/oy77n55brvk72tnlb2bjzfs9nz3cfd0s>