docs: add JSDoc headers to all externally exported store functions

src/store/article/createUnderParent.js

@@ -7,6 +7,18 @@ import nextSku from '../numbers/nextSku.js';
 import request from '../request.js';
 import slugify from '../slugify.js';
 
+/**
+ * Creates a new article under a given parent category, allocating a SKU and
+ * a default unit.
+ *
+ * @param {object} pool - The mssql connection pool.
+ * @returns {Function} An async function that creates an article.
+ *
+ * @example
+ * const fn = createUnderParent(pool);
+ * const article = await fn({ googleAuthId: 42, parentId: 5, name: 'Cola' });
+ * // => { id, parentId, name, sku }
+ */
 export default function createUnderParent(pool) {
   const access = resolveCategoryAccess(pool);
   const ensureUnit = ensureDefaultUnit(pool);