title: error when try install byebug
body: <p>I get the error when I try to install byebug.
  What's the reason for this?</p>
  
  <pre><code>sudo gem install byebug -v '10.0.1'
  Building native extensions. This could take a while...
  ERROR:  Error installing byebug:
      ERROR: Failed to build gem native extension.
  
      current directory: /var/lib/gems/2.3.0/gems/byebug-10.0.1/ext/byebug
  /usr/bin/ruby2.3 -r ./siteconf20180326-12662-69j4pj.rb extconf.rb
  mkmf.rb can't find header files for ruby at /usr/lib/ruby/include/ruby.h
  
  extconf failed, exit code 1
  
  Gem files will remain installed in /var/lib/gems/2.3.0/gems/byebug-10.0.1 for inspection.
  Results logged to /var/lib/gems/2.3.0/extensions/x86-linux/2.3.0/byebug-10.0.1/gem_make.out
  </code></pre>