We are going to rename sal-rest-docgen module to restconf-openapi to better express that this is an OpenAPI documentation of the Restconf project. Generally we are moving all packages from org.opendaylight.netconf.sal.rest.doc to org.opendaylight.restconf.openapi.

We need to create the following patches:

1. Change artifactId in sal-rest-docgen pom.xml to be restconf-openapi and rename folder
2. Refactor package org.opendaylight.netconf.sal.rest.doc.api to org.opendaylight.restconf.openapi.api
3. Refactor package org.opendaylight.netconf.sal.rest.doc.impl to org.opendaylight.restconf.openapi.impl
4. Refactor package org.opendaylight.netconf.sal.rest.doc.jaxrs to org.opendaylight.restconf.openapi.jaxrs
5. Refactor package org.opendaylight.netconf.sal.rest.doc.model.builder to org.opendaylight.restconf.openapi.model.builder
6. Refactor package org.opendaylight.netconf.sal.rest.doc.mountpoints to org.opendaylight.restconf.openapi.mountpoints
7. Refactor package org.opendaylight.netconf.sal.rest.doc.openapi to org.opendaylight.restconf.openapi.model
8. Refactor package org.opendaylight.netconf.sal.rest.doc.u`til to org.opendaylight.restconf.openapi.util

In addition, in step #7 we are renaming openapi package to model because openapi is now a module name and we are expressing that we are storing here Java classes that are used to model OpenAPi objects.