Audit 5.0 REST API docs to see where urgent updates are required

There is an ongoing project to update the REST API docs, however there are a few pages which will need updates in the very short-term in order for people to be able to use them. This ticket is to track which pages need updating for 5.0 in order to use them correctly:

• https://developer.couchbase.com/documentation/server/5.0/rest-api/rest-bucket-create.html
• https://developer.couchbase.com/documentation/server/5.0/rest-api/rest-bucket-parameters.html
• https://developer.couchbase.com/documentation/server/5.0/rest-api/post-settings-indexes.html
• https://developer.couchbase.com/documentation/server/5.0/rest-api/rbac.html