Update spec/registry.md as suggested by @stasm in #814

Author: eemeli

spec/registry.md

@@ -361,8 +361,8 @@ The `:string` function returns the string value of the resolved value of the _op
 
 #### Composition
 
-When an _operand_ or an _option_ value uses a _variable_ with a _declaration_
-using an _expression_ with a `:string` _annotation_,
+When an _operand_ or an _option_ value uses a _variable_ annotated,
+directly or indirectly, by a `:string` _annotation_,
 its resolved value contains only the string value of the _operand_ of the annotated _expression_,
 together with its resolved locale and directionality,
 and no _option_ values.