Add release procedure

[jmesnil]

With the new structure (the wf-to-eap conversion commits that transforms the upstream wildfly-maven-plugin in the eap-maven-plugin), how do we update and release a new version?

This project is missing a release procedure to help understand and do a release by someone without a deep knowledge on the project.

[jmesnil]

tangent: should the project use the wf-to-eap branch as its default branch (main has not been updated for a year)?