refactor: remove unused lines

Author: Steven Chen

Dockerfile

@@ -19,8 +19,3 @@ RUN \
   gem update --system && \
   cd /opt/build && \
   /bin/bash build.sh
-#  bundle install --path vendor/bundle && \
-#  cd vendor/bundle/ruby && \
-#  tar zcvf nokogiri-1.8.2.tar.gz 2.2.0/extensions/x86_64-linux/2.2.0-static/nokogiri-1.8.2 && \
-#  mv nokogiri-1.8.2.tar.gz /opt/build && \
-#  cd -

README.md

@@ -41,4 +41,4 @@ $ docker build -t rubygem-native-builder .
 $ docker cp rubygem-native-builder:/opt/build/target /path/to/host/directory
 ```
 
-Have fun!
+Currently, it only builds native extensions for `x86_64` Linux. Have fun!