Use standard DISCLAIMER

Reference: https://incubator.apache.org/policy/incubation.html

Author: DemesneGH

DISCLAIMER

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+Apache Teaclave (incubating) is an effort undergoing incubation at The Apache
+Software Foundation (ASF), sponsored by the Apache Incubator.
+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.