remove DISCLAIMER-WIP

most licenses have been converted to Apache and the non Apache
licenses have been documented.
We can assume that now it should be the time to remove DISCLAIMER-WIP

Signed-off-by: Alin Jerpelea <alin.jerpelea@sony.com>

DISCLAIMER-WIP

@@ -1,20 +0,0 @@
-Apache NuttX 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.
-
-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 known issues the project is currently aware of (note that this list, by definition,
-is likely to be incomplete):
-
- * Releases may have incomplete licensing conditions.
- * Some ASF files still have BSD headers.  Most of the top contributors have signed an ICLA and
-   we are working on updating the headers and getting approvals from other copyright holders.
-
-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/nuttx.html