Restore X API pages missing after Chat docs overlay

Bring back x-api/overview and other nav targets so the X API product
API Reference tab does not 404 on the first page.

Author: tcaldwell-x

x-api/activity/delete-x-activity-subscriptions-by-ids.mdx

@@ -0,0 +1,3 @@
+---
+openapi: delete /2/activity/subscriptions
+---

x-api/articles/create-draft-article.mdx

@@ -0,0 +1,3 @@
+---
+openapi: post /2/articles/draft
+---

x-api/articles/introduction.mdx

@@ -0,0 +1,72 @@
+---
+title: Introduction
+description: "Use the X API Articles endpoints to programmatically create draft long-form Articles with rich text, media, and embeds, then publish them to X."
+sidebarTitle: Introduction
+keywords: ["articles", "articles API", "long-form", "long-form posts", "create article", "draft article", "publish article", "write articles"]
+---
+
+The Articles endpoints allow developers to create draft Articles and publish them on X programmatically. Articles are long-form posts that support rich text formatting, embedded posts, links, and images.
+
+These endpoints require user-auth authentication via OAuth 1.0a or OAuth 2.0 PKCE with the `tweet.read`, `tweet.write`, and `users.read` scopes.
+
+Currently, the API supports two endpoints:
+
+## Create a draft Article
+
+Developers can create a new draft Article using the `POST https://api.x.com/2/articles/draft` endpoint. The request body contains the article title, the body content as a [DraftJS](https://draftjs.org/docs/api-reference-content-state) content state of text blocks and entities, and optional cover media uploaded via the [media upload endpoints](/x-api/media/introduction).
+
+## Publish an Article
+
+Once a draft is ready, developers can make it publicly visible using the `POST https://api.x.com/2/articles/{article_id}/publish` endpoint, where `article_id` is the ID returned when the draft was created.
+
+## Getting started
+
+To use the endpoints, you need a user access token. For details on generating one, see the [OAuth 2.0 Authorization Code Flow with PKCE](/fundamentals/authentication/oauth-2-0/authorization-code) documentation.
+
+Once you have the access token, you can create a draft Article as shown below:
+
+```bash
+curl --request POST 'https://api.x.com/2/articles/draft' \
+  --header 'Authorization: Bearer XXXXX' \
+  --header 'Content-Type: application/json' \
+  --data '{
+    "title": "My first Article",
+    "content_state": {
+      "blocks": [
+        {
+          "text": "Hello from the Articles API!",
+          "type": "unstyled"
+        }
+      ],
+      "entities": []
+    }
+  }'
+```
+
+If the request is successful, you should see the JSON response as shown below:
+
+```json
+{
+  "data": {
+    "id": "1146654567674912769",
+    "title": "My first Article"
+  }
+}
+```
+
+You can then publish the draft using the returned Article ID:
+
+```bash
+curl --request POST 'https://api.x.com/2/articles/1146654567674912769/publish' \
+  --header 'Authorization: Bearer XXXXX'
+```
+
+If the request is successful, the response contains the ID of the post created for the published Article:
+
+```json
+{
+  "data": {
+    "post_id": "1346889436626259968"
+  }
+}
+```

x-api/articles/publish-article.mdx

@@ -0,0 +1,3 @@
+---
+openapi: post /2/articles/{article_id}/publish
+---