added FusionCalculator as submodule

README.md

@@ -0,0 +1,19 @@
+# SharpCalculator
+A calculator application written in C# and Fusion.
+Using Avalonia to draw GUI.
+
+## Building
+1. ensure that [FusionCalculator](https://github.com/Timerix22/FusionCalculator) submodule is up-to-date.
+    ```shell
+    git submodule init && git submodule update
+    ```
+2. Translate FusionCalculator to C#
+    ```shell
+    cd FusionCalculator
+    ./build_cs.sh --translate-only
+    cd ..
+    ```
+3. Build graphical application
+    ```shell
+    dotnet build -c release SharpCalculator.Avalonia/SharpCalculator.Avalonia.csproj 
+    ```