chore(docs): Refine descriptions of the domain
chore(docs): Refine descriptions of the domain

This refines the descriptions of the domain trying explain in Camel
terms Syndesis domain model. Also updates the links to Syndesis GitHub
repositories.

rhuss/ipaas-rest,redhat-ipaas/ipaas-api-java,chirino/ipaas-rest,rhuss/ipaas-rest,redhat-ipaas/ipaas-rest,chirino/ipaas-rest,redhat-ipaas/ipaas-api-java,KurtStam/ipaas-rest,KurtStam/ipaas-rest,KurtStam/syndesis-rest,chirino/ipaas-rest,KurtStam/syndesis-rest,redhat-ipaas/ipaas-rest,redhat-ipaas/ipaas-rest,rhuss/ipaas-rest,KurtStam/syndesis-rest,KurtStam/ipaas-rest