Add support for all mdast-util-toc options

Such as `ordered`, `prefix`, and `parents`, plus everything that might
be added in the future.

Related to GH-31.

index.js

@@ -4,24 +4,18 @@ var util = require('mdast-util-toc')
 
 module.exports = toc
 
-var defaultHeading = 'toc|table[ -]of[ -]contents?'
-
 function toc(options) {
   var settings = options || {}
-  var heading = settings.heading || defaultHeading
-  var depth = settings.maxDepth || 6
-  var tight = settings.tight
-  var skip = settings.skip
 
   return transformer
 
   function transformer(node) {
-    var result = util(node, {
-      heading: heading,
-      maxDepth: depth,
-      tight: tight,
-      skip: skip
-    })
+    var result = util(
+      node,
+      Object.assign({}, settings, {
+        heading: settings.heading || 'toc|table[ -]of[ -]contents?'
+      })
+    )
 
     if (result.index === null || result.index === -1 || !result.map) {
       return

readme.md

@@ -90,26 +90,8 @@ Generate a table of contents.
 
 ##### `options`
 
-###### `options.heading`
-
-`string?`, default: `'toc|table[ -]of[ -]contents?'` — Heading to look for,
-wrapped in `new RegExp('^(' + value + ')$', 'i')`.
-
-###### `options.maxDepth`
-
-`number?`, default: `6` — Maximum heading depth to include in the table of
-contents, This is inclusive, thus, when set to `3`, level three headings,
-are included (those with three hashes, `###`).
-
-###### `options.tight`
-
-`boolean?`, default: `false` — Whether to compile list-items tightly.
-
-###### `options.skip`
-
-`string?` — Headings to skip, wrapped in `new RegExp('^(' + value + ')$', 'i')`.
-Any heading matching this expression will not be present in the table of
-contents.
+All options are passed to [`mdast-util-toc`][util], with the exception that
+`heading` defaults to `'toc|table[ -]of[ -]contents?'`.
 
 ## Security
 
@@ -225,3 +207,5 @@ abide by its terms.
 [rehype]: https://github.com/rehypejs/rehype
 
 [hast]: https://github.com/syntax-tree/hast
+
+[util]: https://github.com/syntax-tree/mdast-util-toc#options