Tweak badges and compiler support in the README

Author: Morwenn

README.md

@@ -1,6 +1,5 @@
-[![Latest Release](https://img.shields.io/badge/release-cpp--TimSort%2F1.2.1-blue.svg)](https://github.com/timsort/cpp-TimSort/releases/tag/v1.2.1)
-[![Conan Package](https://img.shields.io/badge/conan-1.2.1-blue.svg)](https://conan.io/center/timsort?version=1.2.1)
-[![License](https://img.shields.io/:license-mit-blue.svg)](https://doge.mit-license.org)
+[![Latest Release](https://img.shields.io/badge/release-1.2.1-blue.svg)](https://github.com/timsort/cpp-TimSort/releases/tag/v1.2.1)
+[![Conan Package](https://img.shields.io/badge/conan-cpp--TimSort%2F1.2.1-blue.svg)](https://conan.io/center/timsort?version=1.2.1)
 
 ## TimSort
 
@@ -44,19 +43,23 @@ gfx::timsort(vec.begin(), vec.end(), std::less<size_t>(), &len);
 
 ## INSTALLATION & COMPATIBILITY
 
+![Ubuntu builds status](https://github.com/timsort/cpp-TimSort/workflows/Ubuntu%20Builds/badge.svg?branch=1.x.y)
+![Windows builds status](https://github.com/timsort/cpp-TimSort/workflows/Windows%20Builds/badge.svg?branch=1.x.y)
+![MacOS builds status](https://github.com/timsort/cpp-TimSort/workflows/MacOS%20Builds/badge.svg?branch=1.x.y)
+
 This library is compatible with C++98, but if you compile it with C++11 or higher it will try to use `std::move()`
 when possible instead of copying vaues around, which notably allows to sort collections of move-only types (see
 [#9](https://github.com/gfx/cpp-TimSort/pull/9) for details).
 
 You can explicity control the use of `std::move()` by setting the macro `GFX_TIMSORT_USE_STD_MOVE` to `0` or `1`.
 
 The library has been tested with the following compilers:
-* GCC 5
-* Clang 3.8
-* Xcode 9.2 AppleClang
-* MSVC 2017 update 9
+* GCC 5.5
+* Clang 6
+* MSVC 2017
 
-It should also work with more recent compilers, and most likely with some older compilers too.
+It should also work with more recent compilers, and most likely with some older compilers too. We used to guarantee
+support as far back as Clang 3.8, but the new continuous integration environment doesn't go that far.
 
 The library can be installed on the system via CMake with the following commands: