add comment for unusual code

Author: FireLemons

Dockerfile

@@ -25,6 +25,7 @@ RUN apk update && apk upgrade && apk add --update --no-cache \
   postgresql-client \
   tzdata \
   vim && rm -rf /var/cache/apk/*
+# The ruby alpine image's apk doesn't have the current version of node
 RUN apk add  --no-cache --repository http://dl-cdn.alpinelinux.org/alpine/edge/main/ nodejs=22.11.0-r0 npm
 
 WORKDIR $RAILS_ROOT