fix(docker): send ROBOTS_NOINDEX as a header, make COMPRESSION_MODE work and fix the Docker guide example

Dockerfile.nonroot

@@ -21,7 +21,7 @@ ARG SIMPLE_MODE=false
 ENV SIMPLE_MODE=$SIMPLE_MODE
 ARG DISABLE_GITHUB_STARS=false
 ENV DISABLE_GITHUB_STARS=$DISABLE_GITHUB_STARS
-ARG COMPRESSION_MODE=all
+ARG COMPRESSION_MODE=o
 ENV COMPRESSION_MODE=$COMPRESSION_MODE
 
 ARG BASE_URL