Refactor code-style

*   Add more docs to JSDoc

Author: wooorm

lib/index.js

@@ -5,6 +5,14 @@
 
 import {convert} from 'unist-util-is'
 
+/**
+ * Check if the given value is phrasing content.
+ *
+ * @param
+ *   Thing to check, typically `Node`
+ * @returns
+ *   Whether `node` is phrasing content.
+ */
 export const phrasing = /** @type {AssertPredicatePhrasing} */ (
   convert([
     'break',