Refactor docs

Author: wooorm

lib/index.js

@@ -16,6 +16,10 @@ const emptyOptions = 'yaml'
 /**
  * Add support for frontmatter.
  *
+ * ###### Notes
+ *
+ * Doesn’t parse the data inside them: create your own plugin to do that.
+ *
  * @param {Options | null | undefined} [options='yaml']
  *   Configuration (default: `'yaml'`).
  * @returns {undefined}