Add description about additional config elements

freva/src/drs/metadata/custom.rs

@@ -72,7 +72,8 @@ lazy_static! {
 /// joining sections is not supported.
 ///
 /// All part names are accepted directly as strings and will have no verification for correctness or conformity to any
-/// existing DRS specification in terms of allowed values.
+/// existing DRS specification in terms of allowed values. Additional names are also allowed but are ignored. This can
+/// be used to mark out parts of the path/name that aren't used for DRS data.
 #[derive(Debug, Clone)]
 pub struct ComponentConfig {
     /// The keys of the different path segments in the order they are expected to appear in the path. This does not