const-eval.const-context.outer-generics: make more clear/obvious

The wording took some shortcuts that I think are not worth it

Author: tshepang

src/const_eval.md

@@ -258,7 +258,7 @@ r[const-eval.const-context.block]
 * A [const block]
 
 r[const-eval.const-context.outer-generics]
-Const contexts that are used as parts of types (array type and repeat length expressions as well as const generic arguments) can only make restricted use of surrounding generic parameters: such an expression must either be a single bare const generic parameter, or an arbitrary expression not making use of any generics.
+Const contexts that are used as parts of types (array type expressions, array repeat length expressions, and const generic arguments) can only make restricted use of surrounding generic parameters: such an expression must either be a single bare const generic parameter, or an arbitrary expression not making use of any generics.
 
 r[const-eval.const-fn]
 ## Const functions