[DISCUSS]Add separated selectable version to our documents

[??????]

Hi, all:
   We had implement many new features step by step in each release, so I think 
we also need make docs with separated version like :
  
 --------------------------------------------
 User guide                version : 1.0.0 ??
 --------------------------------------------
  
 document content ...
  
  
  
 --------------------------------------------
  
   Then user can clear known any feature in which version implemented, Any 
thoughts ?
  
 Best Regards & Thanks
 YangYongZheng