Remove link to Community Q&A and Twitter (line#780)

- Community Q&A site was closed.
- The SDK team no longer posts information to Twitter

Author: tokuhirom

README.md

@@ -31,12 +31,8 @@ $ npm install @line/bot-sdk --save
 ## Help and media
 FAQ: https://developers.line.biz/en/faq/
 
-Community Q&A: https://www.line-community.me/questions
-
 News: https://developers.line.biz/en/news/
 
-Twitter: @LINE_DEV 
-
 ## Versioning
 This project respects semantic versioning