chore: add ManageCustomisation perm

package.json

@@ -1,6 +1,6 @@
 {
     "name": "revolt.js",
-    "version": "6.0.4",
+    "version": "6.0.5",
     "main": "dist/index.js",
     "typings": "dist/index.d.ts",
     "module": "esm/index.js",

src/permissions/definitions.ts

@@ -21,8 +21,10 @@ export const Permission = {
     ManagePermissions: 2 ** 2,
     /// Manage roles on server
     ManageRole: 2 ** 3,
+    /// Manage server customisation (includes emoji)
+    ManageCustomisation: 2**4,
 
-    // % 3 bits reserved
+    // % 1 bits reserved
 
     // * Member permissions
     /// Kick other members below their ranking