docs(federation): 📝 Update SDK documentation

packages/sdk/schemas/extensions/emojis.ts

@@ -0,0 +1,25 @@
+/**
+ * Custom emojis extension.
+ * @module federation/schemas/extensions/custom_emojis
+ * @see module:federation/schemas/base
+ * @see https://versia.pub/extensions/custom-emojis
+ */
+import { z } from "zod";
+import { emojiRegex } from "../../regex.ts";
+import { ImageContentFormatSchema } from "../contentformat.ts";
+
+export const CustomEmojiExtensionSchema = z.strictObject({
+    emojis: z.array(
+        z.strictObject({
+            name: z
+                .string()
+                .min(1)
+                .max(256)
+                .regex(
+                    emojiRegex,
+                    "Emoji name must be alphanumeric, underscores, or dashes, and surrounded by identifiers",
+                ),
+            url: ImageContentFormatSchema,
+        }),
+    ),
+});