docs: rm requires sudo

Author: ceefour

src/docs/config-docker.md

@@ -45,7 +45,7 @@ FROM gitpod/workspace-full
 RUN sudo apt-get update \
     && sudo apt-get install -y \
         ... \
-    && rm -rf /var/lib/apt/lists/*
+    && sudo rm -rf /var/lib/apt/lists/*
 
 # Apply user-specific settings
 ENV ...