[docs] add "download" badge (#2224)

* add "download" badge

* Update README.rst

* Update README.md

* replaced issue badge with releases downloads badge

* Update README.md

README.md

@@ -5,11 +5,10 @@ LightGBM, Light Gradient Boosting Machine
 [![Appveyor Build Status](https://ci.appveyor.com/api/projects/status/1ys5ot401m0fep6l/branch/master?svg=true)](https://ci.appveyor.com/project/guolinke/lightgbm/branch/master)
 [![Travis Build Status](https://travis-ci.org/microsoft/LightGBM.svg?branch=master)](https://travis-ci.org/microsoft/LightGBM)
 [![Documentation Status](https://readthedocs.org/projects/lightgbm/badge/?version=latest)](https://lightgbm.readthedocs.io/)
-[![GitHub Issues](https://img.shields.io/github/issues/Microsoft/LightGBM.svg)](https://github.com/microsoft/LightGBM/issues)
 [![License](https://img.shields.io/badge/license-MIT-blue.svg)](https://github.com/microsoft/LightGBM/blob/master/LICENSE)
 [![Python Versions](https://img.shields.io/pypi/pyversions/lightgbm.svg)](https://pypi.org/project/lightgbm)
 [![PyPI Version](https://img.shields.io/pypi/v/lightgbm.svg)](https://pypi.org/project/lightgbm)
-[![Join the chat at https://gitter.im/Microsoft/LightGBM](https://badges.gitter.im/Microsoft/LightGBM.svg)](https://gitter.im/Microsoft/LightGBM?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+[![Join Gitter at https://gitter.im/Microsoft/LightGBM](https://badges.gitter.im/Microsoft/LightGBM.svg)](https://gitter.im/Microsoft/LightGBM?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 [![Slack](https://lightgbm-slack-autojoin.herokuapp.com/badge.svg)](https://lightgbm-slack-autojoin.herokuapp.com)
 
 LightGBM is a gradient boosting framework that uses tree based learning algorithms. It is designed to be distributed and efficient with the following advantages:

python-package/README.rst

 LightGBM Python-package
 =======================
 
-|License| |Python Versions| |PyPI Version|
+|License| |Python Versions| |PyPI Version| |Downloads|
 
 Installation
 ------------
@@ -199,5 +199,6 @@ Documentation strings (docstrings) are written in the NumPy style.
    :target: https://pypi.org/project/lightgbm
 .. |PyPI Version| image:: https://img.shields.io/pypi/v/lightgbm.svg
    :target: https://pypi.org/project/lightgbm
-
+.. |Downloads| image:: https://pepy.tech/badge/lightgbm
+   :target: https://pepy.tech/project/lightgbm
 .. _CMake: https://cmake.org/