As per the guidance in JEP 11 [1], the javadoc for types in
incubator modules should have a clear and explicit warning
notice. To that end, a simple inline taglet can be added that
can be used to effectively inject a standard notice, and apply
it to all public types in the HTTP module ( currently the only
incubating feature ).

This work is, somewhat, in preparation for the move to a
single documentation bundle [2].

[1] http://openjdk.java.net/jeps/11
[2] http://openjdk.java.net/jeps/299