Java 8 Samples that use @WebServlet should probably have a comment about web.xml

[ifigotin]

The samples for Java8 Standard are mostly the same as for Java7, except for @WebServlet.
It may not be obvious to the reader that for Java8 one does not need web.xml when looking at the docs that point to these samples for java7/java8.

Perhaps we should add an additional comment to the samples, saying (in each servlet) that no web.xml is required?

[lesv]

Will add comments in the class files.

[lesv]

Fixed in #692