fix: rollback the SUBNET_PREFIX

documents/docs/02-guide/06-upgrade.md

@@ -51,6 +51,7 @@ grep "SAFELINE_DIR" ".env" > /dev/null || echo "SAFELINE_DIR=$(pwd)" >> ".env"
 grep "IMAGE_TAG" ".env" > /dev/null || echo "IMAGE_TAG=latest" >> ".env"
 grep "MGT_PORT" ".env" > /dev/null || echo "MGT_PORT=9443" >> ".env"
 grep "POSTGRES_PASSWORD" ".env" > /dev/null || echo "POSTGRES_PASSWORD=$(LC_ALL=C tr -dc A-Za-z0-9 </dev/urandom | head -c 32)" >> ".env"
+grep "SUBNET_PREFIX" ".env" > /dev/null || echo "SUBNET_PREFIX=172.22.222" >> ".env"
 grep "IMAGE_PREFIX" ".env" >/dev/null || echo "IMAGE_PREFIX=chaitin" >>".env"
 ```