chore(README): add learning resource
chore(README): add learning resource

RxJS-CN/RxJS-Docs-CN,SangKa/RxJS-Docs-CN,RxJS-CN/RxJS-Docs-CN,RxJS-CN/RxJS-Docs-CN,SangKa/RxJS-Docs-CN,SangKa/RxJS-Docs-CN,RxJS-CN/RxJS-Docs-CN,SangKa/RxJS-Docs-CN