[7.1] DevGuide - 8.2.13. Portable Extensions

Document: https://access.stage.redhat.com/documentation/en/red-hat-jboss-enterprise-application-platform//7.0/development-guide/chapter-8-contexts-and-dependency-injection-cdi

Issue:

• 8.2.13. Portable Extensions has no example.
• Extension are very wide topic and I am not sure it can be easily covered in such tiny paragraph. It contains the very basic information (adequate to this document), but it wouldn't hurt to give the reader a hint where to look for more details.

Solution:
I would link this to Weld doc in order to provide more details. Something like "For more details see Weld documentation."
As for examples, we can just link it to EAP CDI quickstarts - link