Change DISCLAIMER to DISCLAIMER-WIP (#6442)

DISCLAIMER-WIP

@@ -0,0 +1,18 @@
+Apache Gluten (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.
+
+Some of the incubating project’s releases may not be fully compliant with ASF policy.
+For example, releases may have incomplete or un-reviewed licensing conditions.
+What follows is a list of issues the project is currently aware of (this list is likely to be incomplete):
+
+* Releases may have incomplete licensing conditions.
+
+If you are planning to incorporate this work into your product/project, please be aware that you will need to conduct a thorough licensing review to determine the overall implications of including this work. For the current status of this project through the Apache Incubator, visit: https://incubator.apache.org/projects/gluten.html