Adding some details to readme

.gitignore

@@ -89,6 +89,8 @@ skia/viewer/build/windows/dependencies/gl3w
 skia/viewer/build/windows/dependencies/skia
 skia/viewer/build/windows/dependencies/glfw
 skia/viewer/build/windows/dependencies/glfw_build
+skia/viewer/build/windows/dependencies/bin
+skia/viewer/build/windows/bin
 skia/viewer/build/windows/obj
 skia/viewer/build/windows/*.sln
 skia/viewer/build/windows/*.vcxproj

skia/viewer/build/windows/README.md

@@ -0,0 +1,20 @@
+# Rive Windows Viewer
+
+Main entry is [build.bat](build.bat).
+Requirements:
+
+- Git
+  [Download and install](https://git-scm.com/download/win)
+- CMake
+  - [Download and install](https://cmake.org/download/).
+- Python
+
+  - Get [Python 3](https://www.python.org/downloads/). You may need to symlink python3 to python. Make sure to do the custom install and check "install for all users."
+    ```
+    mklink "C:\Program Files\Python310\python3.exe" "C:\Program Files\Python310\python.exe"
+    ```
+
+- Visual Studio 2022 Community Edition
+  - Add clang tools
+  - You may need to patch up the scripts if you have a different version.
+- Install Google's [Depot Tools](https://commondatastorage.googleapis.com/chrome-infra-docs/flat/depot_tools/docs/html/depot_tools_tutorial.html#_setting_up) to build Skia.