extractor doc

docs/extractors/extractor.md

@@ -1,2 +1,44 @@
 # Discord Player Extractor API
-The Extractor API
+The Extractor API allows you to build your own stream extractor for **Discord Player**.
+
+# Example Extractor
+Your extractor should have 2 methods (required):
+ - `validate(query): boolean`
+   
+   This method is called by Discord Player while validating the query provided via `Player.play()`. (Note that only `string` queries are passed to your extractor)
+
+ - `getInfo(query): object`
+   
+   This method is used by Discord Player to create `Track` object. You can return your data here that gets passed to `Track`.
+   Your info must be similar to this:
+
+    ```js
+    {
+        // the title
+        title: "Extracted by custom extractor",
+        // the duration in ms
+        duration: 20000,
+        // the thumbnail
+        thumbnail: data.thumbnail,
+        // engine, can be Readable streams or link to raw stream that gets played
+        engine: data.streamURL,
+        // number of views
+        views: 0,
+        // author of this stream
+        author: data.artist.name,
+        // description
+        description: "",
+        // link of this stream
+        url: data.url
+    }
+    ```
+ - `important: boolean`
+   
+   You can mark your Extractor as `important` by adding `important: true` to your extractor object. Doing this will disable rest of the extractors that comes after your extractor and use your extractor to get data. By default, it is set to `false`.
+
+ - `version: string`
+
+   This should be the version of your extractor. It is not really important and is set to `0.0.0` by default.
+
+# Examples
+### You can check out **[@discord-player/extractor](https://github.com/Snowflake107/discord-player-extractors)**