docs: apply review learnings to graphql-playground.mdx

- Remove em dashes from step 1 sub-bullets (no-em-dash rule)
- Add TODO screenshot placeholder after step 3 (APIs tab)
- Link "Product Catalogues" in step 8 to manage-catalogues page
- Link "Developer App" in credential injection section

Author: sharadregoti

tyk-developer-portal/graphql-playground.mdx

@@ -32,8 +32,8 @@ You can add a GraphQL Schema Definition Language (SDL) file to an API Product to
 
    If you don't have an existing GraphQL API, use the built-in Star Wars example from the Tyk Dashboard:
    - Navigate to **APIs > Add New API**, click **Try example**, select **Star Wars GQL API**, and click **Use Example**
-   - Copy the **Key ID** from the confirmation pop-up and save it — you will use this as the auth header when testing in the Playground
-   - Go to the **Schema** tab of the newly created API and download the schema file — you will upload this as the SDL file in step 5
+   - Copy the **Key ID** from the confirmation pop-up and save it; you will use this as the auth header when testing in the Playground
+   - Go to the **Schema** tab of the newly created API and download the schema file; you will upload this as the SDL file in step 5
 
    <img src="/img/graphql-api-star-wars-schema.png" alt="GraphQL API Schema Tab" />
 
@@ -44,6 +44,8 @@ You can add a GraphQL Schema Definition Language (SDL) file to an API Product to
    - **Choose authentication method**: match the authentication configured on your GraphQL API
    - **Select APIs**: check your GraphQL API from the list
 
+   {/* TODO: Screenshot — APIs tab showing a GraphQL API selected, with provider and authentication method dropdowns populated */}
+
 4. Go to the **Documentation** tab and click **Add API specification**.
 
 5. Set the specification type to **GraphQL SDL**, then upload your schema file.
@@ -62,7 +64,7 @@ You can add a GraphQL Schema Definition Language (SDL) file to an API Product to
 
 7. Click **Save Changes**.
 
-8. Open your **Live Portal**, go to **Product Catalogues**, locate the product, and click **Docs**.
+8. Open your **Live Portal**, go to [**Product Catalogues**](/tyk-stack/tyk-developer-portal/enterprise-developer-portal/managing-access/manage-catalogues), locate the product, and click **Docs**.
 
    <img src="/img/graphql-docs-live-portal.png" alt="GraphQL API Docs Live Portal" />
 
@@ -114,7 +116,7 @@ From v1.16.0, [Universal Data Graph (UDG)](/api-management/graphql/universal-dat
 
 ## Credential Injection in the Playground
 
-When a consumer's Developer App has been approved to access a Product, their credentials are automatically pre-populated in the Playground's HTTP headers. No additional configuration is required.
+When a consumer's [Developer App](/portal/developer-app) has been approved to access a Product, their credentials are automatically pre-populated in the Playground's HTTP headers. No additional configuration is required.
 
 The header format matches the authentication scheme of the APIs in the Product. For example, for an Auth Token API the Playground injects: