Fix link to Amalgamated wiki article (#1064)

Author: kimsey0

README.md

@@ -43,7 +43,7 @@ You can download and install JsonCpp using the [vcpkg](https://github.com/Micros
 The JsonCpp port in vcpkg is kept up to date by Microsoft team members and community contributors. If the version is out of date, please [create an issue or pull request](https://github.com/Microsoft/vcpkg) on the vcpkg repository.
 
 ### Amalgamated source
-https://github.com/open-source-parsers/jsoncpp/wiki/Amalgamated
+https://github.com/open-source-parsers/jsoncpp/wiki/Amalgamated-(Possibly-outdated)
 
 ### The Meson Build System
 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/jsoncpp), or simply use `meson wrap install jsoncpp`.