update Python User Guide and Scala User Guide with supported platforms info (#3593)

* Update python.md

* Update scala.md

* Update python.md

* Update scala.md

* Update python.md

* Update scala.md

* Update python.md

* Update scala.md

* Update python.md

* Update python.md

* Update scala.md

docs/readthedocs/source/doc/UserGuide/python.md

@@ -1,6 +1,8 @@
 # Python User Guide
 
 ---
+Supported Platforms: Linux and macOS.   _**Note:** Windows is currently not supported._
+ 
 ### **1. Install**
 - We recommend using [conda](https://docs.conda.io/projects/conda/en/latest/user-guide/install/) to prepare the Python environment as follows:
 

docs/readthedocs/source/doc/UserGuide/scala.md

@@ -1,6 +1,7 @@
 # Scala User Guide
 
 ---
+Supported Platforms: Linux and macOS. _**Note:** Windows is currently not supported._
  
 ### **1. Try BigDL Examples**
 This section will show you how to download BigDL prebuild packages and run the build-in examples.