docs: add Partial typedef (#6029)

src/structures/MessageEmbed.js

@@ -14,6 +14,13 @@ class MessageEmbed {
    * @param {MessageEmbed|MessageEmbedOptions} [data={}] MessageEmbed to clone or raw embed data
    */
 
+  /**
+   * A `Partial` object is a representation of any existing object.
+   * This object contains between 0 and all of the original objects parameters.
+   * This is true regardless of whether the parameters are optional in the base object.
+   * @typedef {Object} Partial
+   */
+
   /**
    * Represents the possible options for a MessageEmbed
    * @typedef {Object} MessageEmbedOptions