Fixed generation of documentation via Maven Plugin.

Now including .asciidoctorconfig so that generation
and IDEs render the documentation correctly.

Signed-off-by: Simone Bordet <simone.bordet@gmail.com>

jetty-documentation/src/main/asciidoc/embedded-guide/index.adoc

@@ -58,6 +58,7 @@ endif::[]
 // suppress automatic id generation
 :sectids!:
 
+include::.asciidoctorconfig[]
 include::client/client.adoc[]
 include::server/server.adoc[]
 include::io-arch.adoc[]