Add comment on inferProvider call

This is to clarify the expectations on this function.

Signed-off-by: Juan Antonio Osorio <[email protected]>

internal/controlplane/common.go

@@ -135,6 +135,9 @@ func getNameFilterParam(in *pb.Context) sql.NullString {
 	}
 }
 
+// given a list of providers, inferProvider will validate the filter and
+// return the provider if it can be inferred. Note that this assumes that validation
+// has already been made and that the list of providers is not empty.
 func inferProvider(providers []db.Provider, nameFilter sql.NullString) (db.Provider, error) {
 	if !nameFilter.Valid {
 		if len(providers) == 1 {