Clarify naming convention when `@Metric` applies to a parameter

[tjquinno]

The spec describes the annotated naming conventions (https://download.eclipse.org/microprofile/microprofile-metrics-5.0.0/microprofile-metrics-spec-5.0.0.html#annotated-naming-convention) for all combinations of whether or not the developer specifies a name with the annotation and whether or not the naming is to be absolute.

This section fully addresses the use of "non-injecting" annotations such as @Counted but does not mention the convention for injected parameters, with or without an accompanying @Metric annotation.

(In practice, most developers will likely specify @Metric with at least a name on an injected parameter in case the parameter name is not available at runtime.)

The spec could be clearer about the naming convention applied to parameters.