copy changes, add toc, tweak ads placement

docs/getting-started/download.md

@@ -7,18 +7,25 @@ group: getting-started
 
 **Bootstrap v{{ site.current_version}}** is available for download in several ways, including some of your favorite package managers. Choose from the options below to snag just what you need.
 
-### Bootstrap CSS and JS
+{% include ads.html %}
+
+## Contents
+
+* Will be replaced with the ToC, excluding the "Contents" header
+{:toc}
+
+## Bootstrap CSS and JS
 
 **Download Bootstrap's ready-to-use code to easily drop into your project.** Includes compiled and minified versions of all our CSS bundles (default, flexbox-enabled, grid only, or Reboot only) and JavaScript plugins. Doesn't include documentation or source files.
 
 <a href="{{ site.download.dist }}" class="btn btn-lg btn-bs btn-outline" onclick="ga('send', 'event', 'Getting started', 'Download', 'Download Bootstrap');">Download Bootstrap</a>
 
-### Source files
+## Source files
 **Want to compile Bootstrap with your project's asset pipeline?** Choose this option to download our source Sass, JavaScript, and documentation files. Requires a Sass compiler, [Autoprefixer](https://github.com/postcss/autoprefixer), [postcss-flexbugs-fixes](https://github.com/luisrudge/postcss-flexbugs-fixes), and [some setup]({{ site.baseurl }}/getting-started/build-tools/#tooling-setup).
 
 <a href="{{ site.download.source }}" class="btn btn-bs btn-outline" onclick="ga('send', 'event', 'Getting started', 'Download', 'Download source');">Download source</a>
 
-### Bootstrap CDN
+## Bootstrap CDN
 
 Skip the download and use the Bootstrap CDN to deliver Bootstrap's compiled CSS and JS to your project.