Migration Guide currently doesn't contain information about changes in Infinispan subsystem configuration. There's a lot of them and they are best viewed from a diff of Infinispan schemas. Something like this would work (although graphical diffs are prettier):

diff -u jboss-eap-6.4.0/docs/schema/jboss-as-infinispan_1_5.xsd jboss-eap-7.0.0.ER4/docs/schema/jboss-as-infinispan_4_0.xsd

Things that should be documented:

• changes in default configuration values
• deprecated/reworked elements