Fix some broken links

docs/source/api/apollo-server.md

@@ -39,7 +39,7 @@ const server = new ApolloServer({
 | `schemaDirectives` | `Object` | <p>A map of all [custom schema directives](../schema/directives/#using-custom-schema-directives) used in your schema, if any.</p> |
 | `schema` | `Object` | <p>An executable GraphQL schema. You usually don't need to provide this value, because Apollo Server generates it from the `typeDefs` and `resolvers` you provide.</p><p>This field is most commonly used with [Apollo Federation](/federation/implementing-services/#generating-a-federated-schema), which uses a special `buildFederatedSchema` function to generate its schema.</p><p>Note that if you are using [file uploads](../data/file-uploads/), you need to add the `Upload` scalar to your schema manually before providing it here.</p> |
 | `persistedQueries` | `Object` or `false` | <p>If you're using [automated persisted queries (APQ)](../performance/apq/), you can provide an object with a `cache` field as the value of this option to customize where Apolllo Server stores the mapping between operation hashes and query strings.</p><p>Provide `false` to disable APQ entirely.</p> |
-| `subscriptions` | `Object` or `String` or `false` | <p>Provide a `String` to specify the server's subscription-specific endpoint, or an `Object` to further [configure subscription behavior]().</p><p>Provide `false` to disable subscription operations entirely.</p>  |
+| `subscriptions` | `Object` or `String` or `false` | <p>Provide a `String` to specify the server's subscription-specific endpoint, or an `Object` to further [configure subscription behavior](#subscription-configuration-fields).</p><p>Provide `false` to disable subscription operations entirely.</p>  |
 | `rootValue` | `Any` or `Function` | <p>A value or function called with the parsed `Document`, creating the root value passed to the GraphQL executor.</p><p>Providing a function is useful if you want to use a different root value depending on the operation's details, such as whether it's a query or mutation.</p> |
 | `validationRules` | `Object` | <p>An object containing custom functions to use as additional [validation rules](https://github.com/graphql/graphql-js/tree/master/src/validation/rules) when validating the schema.</p> |
 

docs/source/data/resolvers.mdx

@@ -355,7 +355,7 @@ Resolver functions take the following positional arguments, in order:
 
 | Argument  | Description  |
 |---|---|
-| `parent` | <p>The return value of the resolver for this field's parent (i.e., the previous resolver in the [resolver chain](#resolver-chains)).</p><p>For resolvers of top-level fields with no parent (such as fields of `Query`), this value is obtained from the `rootValue` function passed to [Apollo Server's constructor](/api/apollo-server/#apolloserver).</p>  |
+| `parent` | <p>The return value of the resolver for this field's parent (i.e., the previous resolver in the [resolver chain](#resolver-chains)).</p><p>For resolvers of top-level fields with no parent (such as fields of `Query`), this value is obtained from the `rootValue` function passed to [Apollo Server's constructor](/api/apollo-server/#constructoroptions-apolloserver).</p>  |
 | `args` |  <p>An object that contains all GraphQL arguments provided for this field.</p><p> For example, when executing `query{ user(id: "4") }`, the `args` object passed to the `user` resolver is `{ "id": "4" }`.</p> |
 | `context` | <p>An object shared across all resolvers that are executing for a particular operation. Use this to share per-operation state, including authentication information, dataloader instances, and anything else to track across resolvers. </p><p>See [The `context` argument](#the-context-argument) for more information.</p> |
 | `info` | <p>Contains information about the operation's execution state, including the field name, the path to the field from the root, and more. </p><p>Its core fields are listed in the [GraphQL.js source code](https://github.com/graphql/graphql-js/blob/master/src/type/definition.js#L917-L928), and it is extended with additional functionality by other modules, like [`apollo-cache-control`](https://github.com/apollographql/apollo-server/tree/570f548b887/packages/apollo-cache-control).</p> |
@@ -386,7 +386,7 @@ const server = new ApolloServer({
 }
 ```
 
-> The fields of the object passed to your `context` function differ if you're using middleware besides Express. [See the API reference for details.](/api/apollo-server/#apolloserver)
+> The fields of the object passed to your `context` function differ if you're using middleware besides Express. [See the API reference for details.](/api/apollo-server/#middleware-specific-context-fields)
 
 Context initialization can be asynchronous, allowing database connections and other operations to complete:
 

docs/source/federation/gateway.mdx

@@ -120,7 +120,7 @@ server.listen().then(({ url }) => {
 
 </ExpansionPanel>
 
-> The fields of the object passed to your `context` function differ if you're using middleware besides Express. [See the API reference for details.](/api/apollo-server/#apolloserver)
+> The fields of the object passed to your `context` function differ if you're using middleware besides Express. [See the API reference for details.](/api/apollo-server/#middleware-specific-context-fields)
 
 The `buildService` function enables us to customize the requests that are sent to our implementing services. In this example, we return a custom `RemoteGraphQLDataSource`. The datasource allows us to modify the outgoing request with information from the Apollo Server `context` before it's sent. Here, we add the `user-id` header to pass an authenticated user ID to downstream services.