fix links

Author: renejeglinsky

guides/providing-services.md

@@ -95,7 +95,7 @@ This way, services become facades to encapsulated domain data, exposing differen
 
 Instead of exposing access to underlying data in a 1:1 fashion, services frequently expose denormalized views, tailored to specific use cases.
 
-For example, the following service definition, undiscloses information about maintainers from end users and also [marks the entities as `@readonly`](#readonly):
+For example, the following service definition, undiscloses information about maintainers from end users and also [marks the entities as `@readonly`](services/constraints#readonly):
 
 ```cds
 using { sap.capire.bookshop as my } from '../db/schema';

node.js/events.md

@@ -431,7 +431,7 @@ this.on('CREATE', Books, req => {
 ```
 
 ::: details **Best Practice:**{.good} Use the `@mandatory` annotation instead.
-The sample above is just for illustration. Instead, use the [`@mandatory`](../guides/providing-services.md#mandatory)
+The sample above is just for illustration. Instead, use the [`@mandatory`](../guides/services/constraints#mandatory)
 annotation in your CDS model to define mandatory inputs like that:
 
 ```cds