[Docs] Fix errors in the REST guide

In REST API document, 2.1.1.1 point the URL of infinispan-config-8.4.xsd should be https://infinispan.org/schemas/infinispan-config-14.0.xsd

In 2.5.3, 2.5.4 and 2.5.5 points - the commands always give 404 Resource not found response, eventhough I am giving correct cacheManager and cache name.

In 2.9.5 - the PUT command misses /rest at the beginning. NOw it looks like
/v2/security/roles/some_principal?action=grant&role=role1&role=role2
but should be
/rest/v2/security/roles/some_principal?action=grant&role=role1&role=role2
In code snippets under 2.1.1.1 point, the xml, json and yaml configs miss the indexed-entities property as described in my previous comment.

In 2.1.9 point, the sentence Add the full parameter to obtain values and type information: was a bit non-understandable. I would write Add the full=true parameter to obtain values and type information: