chore: update contributors

Author: daviddias

package.json

@@ -72,6 +72,8 @@
     "Sangwon Hong <qpakzk@gmail.com>",
     "Stephen Whitmore <stephen.whitmore@gmail.com>",
     "Thiago Delgado <thiagodelgado111@gmail.com>",
+    "Volker Mische <volker.mische@gmail.com>",
+    "achingbrain <alex@achingbrain.net>",
     "greenkeeperio-bot <support@greenkeeper.io>",
     "haad <haad@headbanggames.com>",
     "kumavis <kumavis@users.noreply.github.com>",