import pkuczynski public key for RVM install (#10140)

import pkuczynski public key for RVM install (#10140)

diff --git a/docs/DEVELOPER-ADVANCED.md b/docs/DEVELOPER-ADVANCED.md
index 2dc64f0..59527a2 100644
--- a/docs/DEVELOPER-ADVANCED.md
+++ b/docs/DEVELOPER-ADVANCED.md
@@ -16,6 +16,7 @@ To get your Ubuntu 16.04 or 18.04 LTS install up and running to develop Discours
 
     # Ruby
     curl -sSL https://rvm.io/mpapis.asc | gpg2 --import -
+    curl -sSL https://rvm.io/pkuczynski.asc | gpg2 --import -
     curl -sSL https://get.rvm.io | bash -s stable
     echo 'gem: --no-document' >> ~/.gemrc
 

GitHub sha: fa8bb5f4

This commit appears in #10140 which was merged by SamSaffron.