Merge pull request #22 from rubytaiwan/add-ruby-central

Add Ruby Central as partner

Author: ryudoawaru

_data/sponsor.yml

@@ -6,6 +6,10 @@
   url: https://evilmartians.com
   name: Evil Martians
   logo: evilmartians.svg
+- type: speaker
+  url: https://rubycentral.org/
+  name: Ruby Central
+  logo: RubyCentral-logo.png
 - type: special
   url: https://www.city.matsue.lg.jp/sangyo_business/sangyoshinko/RubyCityMATSUE/index.html
   name: RubyCityMATSUE