Update branch name to release/1.1 (#443)

* update version to 1.1.0

* correct branch name to release/1.1 in document

Author: HydrogenSulfate

README.md

@@ -36,7 +36,7 @@ PaddleScience 是一个基于深度学习框架 PaddlePaddle 开发的科学计
     # git clone https://gitee.com/paddlepaddle/PaddleScience.git
 
     cd PaddleScience
-    git checkout develop
+    git checkout release/1.1
     export PYTHONPATH=$PWD:$PYTHONPATH
     ```
 

docs/zh/install_setup.md

@@ -43,7 +43,7 @@
     # git clone https://gitee.com/paddlepaddle/PaddleScience.git
 
     cd PaddleScience
-    git checkout develop
+    git checkout release/1.1
     export PYTHONPATH=$PWD:$PYTHONPATH
     ```