Docs: Fix underscores to italic in markdown (#636)

docs/addl-tech.md

@@ -8,7 +8,7 @@
 * We use _Timber_ for logging
 * We use [_Delayed Job_](https://github.com/collectiveidea/delayed_job) for background workers
 * We use _Algolia_ for search
-* We use [\_Redcarpet](https://github.com/vmg/redcarpet) and [Rouge\_](https://github.com/jneen/rouge) for Markdown
+* We use [_Redcarpet_](https://github.com/vmg/redcarpet) and [_Rouge_](https://github.com/jneen/rouge) for Markdown
 * We use _[Carrierwave](https://github.com/carrierwaveuploader/carrierwave)/Fog/AWS S3_ for image upload/storage
 * We use a modified version of [_InstantClick_](http://instantclick.io/) instead of _Turbolinks_
 * We are hosted on _Heroku_