add CI badges to README

README.md

@@ -2,6 +2,24 @@
 
 > std::invoke/std::apply analogs for C++14
 
+[![travis][badge.travis]][travis]
+[![appveyor][badge.appveyor]][appveyor]
+[![language][badge.language]][language]
+[![license][badge.license]][license]
+[![paypal][badge.paypal]][paypal]
+
+[badge.travis]: https://img.shields.io/travis/BlackMATov/invoke.hpp/master.svg?logo=travis&style=for-the-badge
+[badge.appveyor]: https://img.shields.io/appveyor/ci/BlackMATov/invoke-hpp/master.svg?logo=appveyor&style=for-the-badge
+[badge.language]: https://img.shields.io/badge/language-C%2B%2B14-red.svg?style=for-the-badge
+[badge.license]: https://img.shields.io/badge/license-MIT-blue.svg?style=for-the-badge
+[badge.paypal]: https://img.shields.io/badge/donate-PayPal-orange.svg?logo=paypal&colorA=00457C&style=for-the-badge
+
+[travis]: https://travis-ci.org/BlackMATov/invoke.hpp
+[appveyor]: https://ci.appveyor.com/project/BlackMATov/invoke-hpp
+[language]: https://en.wikipedia.org/wiki/C%2B%2B14
+[license]: https://en.wikipedia.org/wiki/MIT_License
+[paypal]: https://www.paypal.me/matov
+
 [invoke]: https://github.com/BlackMATov/invoke.hpp
 
 ## Installation
@@ -25,3 +43,5 @@ Analog of [std::invoke_result](https://en.cppreference.com/w/cpp/types/result_of
 ### `invoke_hpp::apply(F&& f, Tuple&& args)`
 
 Analog of [std::apply](https://en.cppreference.com/w/cpp/utility/apply) from C++17
+
+## [License (MIT)](./LICENSE.md)