Fix parameter scope grammar productions (#569)

Author: RexJaeschke

standard/basic-concepts.md

@@ -558,8 +558,8 @@ The ***scope*** of a name is the region of program text within which it is possi
 
 - The scope of a member declared by an *enum_member_declaration* ([§18.4](enums.md#184-enum-members)) is the *enum_body* in which the declaration occurs.
 - The scope of a parameter declared in a *method_declaration* ([§14.6](classes.md#146-methods)) is the *method_body* of that *method_declaration*.
-- The scope of a parameter declared in an *indexer_declaration* ([§14.9](classes.md#149-indexers)) is the *accessor_declarations* of that *indexer_declaration*.
-- The scope of a parameter declared in an *operator_declaration* ([§14.10](classes.md#1410-operators)) is the *block* of that *operator_declaration*.
+- The scope of a parameter declared in an *indexer_declaration* ([§14.9](classes.md#149-indexers)) is the *indexer_body* of that *indexer_declaration*.
+- The scope of a parameter declared in an *operator_declaration* ([§14.10](classes.md#1410-operators)) is the *operator_body* of that *operator_declaration*.
 - The scope of a parameter declared in a *constructor_declaration* ([§14.11](classes.md#1411-instance-constructors)) is the *constructor_initializer* and *block* of that *constructor_declaration*.
 - The scope of a parameter declared in a *lambda_expression* ([§11.16](expressions.md#1116-anonymous-function-expressions)) is the *lambda_expression_body* of that *lambda_expression*.
 - The scope of a parameter declared in an *anonymous_method_expression* ([§11.16](expressions.md#1116-anonymous-function-expressions)) is the *block* of that *anonymous_method_expression*.