Add Meson related info to README

Add more information about how one can get a Meson wrap file.

Signed-off-by: Kostiantyn Ponomarenko <konstantin.ponomarenko@gmail.com>

README.md

@@ -140,7 +140,7 @@ endif()
 
 :beer: If you are using OS X and [Homebrew](http://brew.sh), just type `brew tap nlohmann/json` and `brew install nlohmann_json` and you're set. If you want the bleeding edge rather than the latest release, use `brew install nlohmann_json --HEAD`.
 
-If you are using the [Meson Build System](http://mesonbuild.com), then you can wrap this repository as a subproject.
+If you are using the [Meson Build System](http://mesonbuild.com), then you can get a wrap file by downloading it from [Meson WrapDB](https://wrapdb.mesonbuild.com/nlohmann_json), or simply use `meson wrap install nlohmann_json`.
 
 If you are using [Conan](https://www.conan.io/) to manage your dependencies, merely add `jsonformoderncpp/x.y.z@vthiery/stable` to your `conanfile.py`'s requires, where `x.y.z` is the release version you want to use. Please file issues [here](https://github.com/vthiery/conan-jsonformoderncpp/issues) if you experience problems with the packages.