Document injector formatting requirement

[jce-redhat]

when defining injectors for controller credential types (see linux/setup.yml example), the infra.controller_configuration.credential_types role has an odd requirement for adding two spaces between jinja brackets in order to pass the bracketed variable through to the credential configuration. see https://github.com/redhat-cop/controller_configuration/tree/devel/roles/credential_types#formating-injectors for details. this caused some confusion for users of this repo who weren't familiar with the requirement, so a comment should be added for clarity where used.

additionally, the {% raw %} {% endraw %} construct is not required when using the infra.controller_configuration.credential_types role and its two space construct.

[taruch]

jce/injector merge closes this issue.