Remove EXECJS_RUNTIME workaround documentation.

README.md

@@ -20,19 +20,6 @@ PDF files are not available in development mode. See below for more information.
 See the [Middleman docs](https://middlemanapp.com/basics/development_cycle/) for
 more information.
-### A known issue with Middleman in local development
-
-There's a [known issue](https://gitlab.com/gitlab-com/www-gitlab-com/issues/842)
-that causes the Middleman server to hang indefinitely when changes are made to 
-certain filetypes. For the time being, you can workaround the issue in development 
-by explicitly setting `EXECJS_RUNTIME` before starting the Middleman server:
-
-```sh
-bundle install
-
-EXECJS_RUNTIME=Node bundle exec middleman
-```
-
 ### Enable livereloading
 When running middleman with the livereload option enabled, it watches your