[docs] Document WebP support for emoji requests

Fixes #7567

- Add information about supported emoji upload formats
- Explain that all emoji formats can be served as WebP
- Recommend WebP for maximum performance and compatibility
- Document how to request still and animated WebP emojis

Author: skidder

docs/resources/emoji.mdx

@@ -30,6 +30,12 @@ An emoji cannot have both subscription roles and non-subscription roles.
 Emojis with subscription roles are considered premium emoji, and count toward a separate limit of 25.  
 Emojis cannot be converted between normal and premium after creation.
 
+###### Emoji Formats
+
+Emojis can be uploaded as JPEG, PNG, GIF, WebP, and AVIF formats. All emojis (regardless of original format) can be served as WebP. We highly recommend that developers request emojis as WebP for maximum performance and compatibility. The Discord client uses WebP for all emojis displayed in-app.
+
+Still WebP emojis can be requested using the `.webp` file extension. For animated WebP emojis, use the `.webp` extension with the `?animated=true` query parameter.
+
 ###### Application-Owned Emoji
 
 An application can own up to 2000 emojis that can only be used by that app.
@@ -110,6 +116,10 @@ Create a new emoji for the guild. Requires the `CREATE_GUILD_EXPRESSIONS` permis
 Emojis and animated emojis have a maximum file size of 256 KiB. Attempting to upload an emoji larger than this limit will fail and return 400 Bad Request and an error message, but not a [JSON status code](/docs/topics/opcodes-and-status-codes#json).
 :::
 
+:::info
+We highly recommend requesting emojis as WebP for maximum performance and compatibility. See [Emoji Formats](#emoji-formats) for more details.
+:::
+
 :::info
 This endpoint supports the `X-Audit-Log-Reason` header.
 :::
@@ -192,6 +202,10 @@ Create a new emoji for the application. Returns the new [emoji](/docs/resources/
 Emojis and animated emojis have a maximum file size of 256 KiB. Attempting to upload an emoji larger than this limit will fail and return 400 Bad Request and an error message, but not a [JSON status code](/docs/topics/opcodes-and-status-codes#json).
 :::
 
+:::info
+We highly recommend requesting emojis as WebP for maximum performance and compatibility. See [Emoji Formats](#emoji-formats) for more details.
+:::
+
 ###### JSON Params
 
 | Field | Type                                     | Description             |