Updated Breno's Slack username

Author: kgodey

content/gsoc-2019/contents.lr

@@ -19,7 +19,7 @@ Before you start writing a proposal, read our [Application Instructions](/gsoc-2
 Here are short bios of each of our 2019 mentors. Please use first names or Slack/IRC nicknames to address mentors; we prefer informality.
 
 * [Alden Page](https://creativecommons.org/author/aldencreativecommons-org/) (`aldenpage` on Slack)
-* [Breno Ferreira](https://creativecommons.org/author/brenoferreira/) (`Breno` on Slack)
+* [Breno Ferreira](https://creativecommons.org/author/brenoferreira/) (`brenoferreira` on Slack)
 * [Hugo Solar](https://creativecommons.org/author/hugocreativecommons-org/) (`hugo` on Slack)
 * [Kriti Godey](https://creativecommons.org/author/kriticreativecommons-org/) (`kriti` on Slack)
 * [Sophine Clachar](https://creativecommons.org/author/sclachar/) (`Sophine` on Slack)