Add documentation to validate function

packages/perseus/src/widgets/categorizer/validate-categorizer.ts

@@ -5,6 +5,14 @@ import type {
     PerseusCategorizerValidationData,
 } from "../../validation.types";
 
+/**
+ * Checks userInput from the categorizer widget to see if the user has selected
+ * a category for each item.
+ * @param userInput - The user's input corresponding to an array of indices that
+ * represent the selected category for each row/item.
+ * @param validationData - An array of strings corresponding to each row/item
+ * @param strings - Used to provide a validation message
+ */
 function validateCategorizer(
     userInput: PerseusCategorizerUserInput,
     validationData: PerseusCategorizerValidationData,