Update bazel version in README

Author: FloopCZ

README.md

@@ -66,7 +66,7 @@ sudo pacman -S cuda cudnn nvidia
 ```
 
 **Warning:** Newer versions of TensorFlow sometimes fail to build with the latest version of Bazel. You may wish
-to install an older version of Bazel (e.g., 2.0.0).
+to install an older version of Bazel (e.g., 3.1.0).
 
 #### 2) Clone this repository
 ```