Add message tags docs page

docs/message-tags.mdx

@@ -0,0 +1,42 @@
+---
+title: Message Tags
+hide_title: true
+---
+
+import RAW from '!!raw-loader!@site/docs/message-tags.mdx';
+import HeaderWithCopyButton from '@site/src/components/HeaderWithCopyButton';
+
+<HeaderWithCopyButton title="Message Tags" sourceMarkdown={RAW} />
+
+Message tags are free-form strings that can be added to messages to use them for filtering.
+
+In some cases, while debugging webhooks, you may want to get a specific message with a certain field or attribute in the payload, beyond it's event type or channel.
+
+## How to use it
+
+To use message tags, simply add the `tags` field to the create message call. For example, if you want to give your users the option to filter messages related to a specific user id, you can add the user id as a tag.
+
+```typescript
+await svix.message.create('app_id', {
+    eventType: "user.signup",
+    tags: ["user_1"],
+    payload: {
+        "user_id": "user_1",
+        "email": "test@example.com"
+    },
+});
+```
+
+Usually, tags contain values that are already present in the payload, such as user ids, order ids, product categories, etc.
+
+Tags will be visible in the Application Portal, and your users will be able to use them to filter messages.
+
+![Message Tags in the Application Portal](./img/message-tags.png)
+
+They can also be used via the API when [listing messages](https://api.svix.com/docs#tag/Message/operation/v1.message.list) or [message attempts](https://api.svix.com/docs#tag/Message-Attempt/operation/v1.message-attempt.list-attempted-messages).
+
+## When not to use it
+
+Tags are not meant as a way to route messages to specific endpoints or specific customers, that's what [event types](./event-types) and [channels](./channels) are for.
+
+Message tags have no impact on message delivery. They are only meant to be used for message filtering.

sidebars.js

@@ -25,6 +25,7 @@ module.exports = {
           ]
         },
         "channels",
+        "message-tags",
         {
           type: 'category',
           label: 'Advanced Endpoint Types',