Created by: Aurelius84

Only migrating en doc from old dir doc/advanced_guides/dygraph_to_static to paddle/guides/dygraph_to_static

http://gzhxy-inf-bce36a39de.gzhxy.baidu.com:8121/documentation/docs/zh/api/index_cn.html?reviewVersion=jenkins-doc_review-1339

• Add debugging_en.md
• Add error_handling_en.md
• Update debugging_cn.md from old dir
• Update error_handling_cn.md
• Update index_en.rst in dygraph_to_static dir