Migration Guide: bad link to Hibernate ORM 5.0 Migration Guide

Chapter 4.6. Hibernate and JPA Migration Changes of the Migration Guide links to https://github.com/hibernate/hibernate-orm/blob/master/migration-guide.adoc which is wrong. That URL currently contains a migration guide for Hibernate 5.1 and is likely to change in the future.

Correct link for Hibernate 5.0 migration guide is https://github.com/hibernate/hibernate-orm/blob/5.0/migration-guide.adoc

(Also, when I found this, I also found a small typo in a following chapter that isn't really worth of a separate JIRA. The chapter 4.7. Hibernate Search Changes says "JBoss EAP 7 ships with Hibernate 5.5.x", but this is only about Hibernate Search. Should say "JBoss EAP 7 ships with Hibernate Search 5.5.x".)