Add vcpkg installation instructions (#353)

* Add vcpkg installation instructions

Author: NancyLi1013

BUILDING.md

@@ -94,6 +94,18 @@ Build Requirements
 
   * If using JDK 11 or later, CMake 3.10.x or later must also be used.
 
+- Vcpkg
+  
+  You can download and install mozjpeg using the [vcpkg](https://github.com/Microsoft/vcpkg) dependency manager:
+
+  git clone https://github.com/Microsoft/vcpkg.git
+  cd vcpkg
+  ./bootstrap-vcpkg.sh
+  ./vcpkg integrate install
+  vcpkg install mozjpeg
+  
+  The mozjpeg 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 If the version is out of date, please [create an issue or pull request](https://github.com/Microsoft/vcpkg) on the vcpkg repository.
+
 
 Out-of-Tree Builds
 ------------------