bower install angular-markdown-directive
Include angular-sanitize.js. It should be located at bower_components/angular-sanitize/.
Include showdown.js. It should be located at bower_components/showdown/.
Include markdown.js provided by this component into your app.
Add btford.markdown as a module dependency to your app.
Insert the btf-markdown directive into your template:

<btf-markdown>
  #Markdown directive
  *It works!*
</btf-markdown>

You can also bind the markdown input to a scope variable:

<div btf-markdown="markdown">
</div>
<!-- Uses $scope.markdown -->

Or include a markdown file:

<div btf-markdown ng-include="'README.md'">
</div>
<!-- Uses content from README.md -->

Options

You can configure the markdownConverterProvider:

angular.module('myApp', [
  'ngSanitize',
  'btford.markdown'
]).
config(['markdownConverterProvider', function (markdownConverterProvider) {
  // options to be passed to Showdown
  // see: https://github.com/coreyti/showdown#extensions
  markdownConverterProvider.config({
    extensions: ['twitter']
  });
}])