Refactor to use @imports

Author: wooorm

lib/index.js

@@ -1,15 +1,9 @@
 /**
- * @typedef {import('mdast-util-from-markdown').CompileContext} CompileContext
- * @typedef {import('mdast-util-from-markdown').Extension} FromMarkdownExtension
- * @typedef {import('mdast-util-from-markdown').Handle} FromMarkdownHandle
- *
- * @typedef {import('mdast-util-to-markdown').Handle} ToMarkdownHandle
- * @typedef {import('mdast-util-to-markdown').Options} ToMarkdownExtension
- *
- * @typedef {import('../index.js').MdxjsEsm} MdxjsEsm
+ * @import {CompileContext, Extension as FromMarkdownExtension, Handle as FromMarkdownHandle} from 'mdast-util-from-markdown'
+ * @import {Handle as ToMarkdownHandle, Options as ToMarkdownExtension} from 'mdast-util-to-markdown'
+ * @import {MdxjsEsm} from 'mdast-util-mdxjs-esm'
  */
 
-// To do: next major: expose functions.
 import {ok as assert} from 'devlop'
 
 /**