Merge pull request #13492 from PaddlePaddle/upload-readme-1

Upload  readme in doc menu

doc/README.md

+# For Readers and Developers
+
+Thanks for reading PaddlePaddle documentation.
+
+Since **September 17th, 2018**, the **0.15.0 and develop** documentation source has been moved to [Fluiddoc Repo](https://github.com/PaddlePaddle/Paddle) and updated in Fluiddoc Repo.
+
+Please turn to Fluiddoc Repo for the latest documentation.