fix nullable receiver links

Author: sarahhaggarty

docs/topics/jvm/java-to-kotlin-nullability-guide.md

@@ -88,7 +88,7 @@ in the scope where the compiler performs the check.
 
 If you don't perform this check, the code will fail to compile with the following message:
 "Only [safe (?.)](null-safety.md#safe-call-operator) or [non-nullable asserted (!!.) calls](null-safety.md#not-null-assertion-operator) are allowed
-on a [nullable receiver](extensions.md#nullable-receiver) of type String?".
+on a [nullable receiver](extensions.md#nullable-receivers) of type String?".
 
 You can write the same shorter – use the [safe-call operator ?. (If-not-null shorthand)](idioms.md#if-not-null-shorthand), 
 which allows you to combine a null check and a method call into a single operation:

docs/topics/null-safety.md

@@ -321,7 +321,7 @@ In such cases, you can use the `!!` operator to explicitly tell the compiler tha
 
 ## Nullable receiver
 
-You can use extension functions with a [nullable receiver type](extensions.md#nullable-receiver), 
+You can use extension functions with a [nullable receiver type](extensions.md#nullable-receivers), 
 allowing these functions to be called on variables that might be `null`.
 
 By defining an extension function on a nullable receiver type, you can handle `null` values within the function itself