Add VS2019 Support for C# Debugging (c_sharp_basics.rst) (#3088)

* Update c_sharp_basics.rst

Add docs showing how VS2019 is supported.   re: https://github.com/godotengine/godot-proposals/issues/371

Co-authored-by: Hugo Locurcio <[email protected]>

getting_started/scripting/c_sharp/c_sharp_basics.rst

@@ -85,6 +85,7 @@ click on **Editor → Editor Settings** and scroll down to
 external editor of choice. Godot currently supports the following
 external editors:
 
+- Visual Studio 2019
 - Visual Studio Code
 - MonoDevelop
 - Visual Studio for Mac
@@ -94,6 +95,10 @@ external editors:
           the `C# extension <https://marketplace.visualstudio.com/items?itemName=ms-vscode.csharp>`_
           to enable features like syntax highlighting and IntelliSense.
 
+
+.. note:: If you are using Visual Studio 2019, you must follow the instructions found in the "Configure VS2019 for Debugging" section below.
+
+
 Creating a C# script
 --------------------
 
@@ -265,3 +270,17 @@ Profiling your C# code
 
 - `Mono log profiler <https://www.mono-project.com/docs/debug+profile/profile/profiler/>`_ is available via `this PR <https://github.com/godotengine/godot/pull/26513>`_
 - External Mono profiler like `JetBrains dotTrace <https://www.jetbrains.com/profiler/>`_ can be used as described `here <https://github.com/godotengine/godot/pull/34382>`_.
+
+Configure VS2019 for Debugging
+-------------------------------
+
+1. Install VS2019 with ```.NET desktop development``` and ```Desktop development with C++``` workloads installed.
+2.  **Ensure that you do not have ```Xamarin``` installed** (do not choose ```Mobile development with .NET``` workload.  Xamarin changes the DLLs used by MonoDebugger, which breaks debugging.
+3. Install the `VSMonoDebugger extension <https://marketplace.visualstudio.com/items?itemName=GordianDotNet.VSMonoDebugger0d62>`_
+4, In VS2019 --> Extensions --> Mono --> Settings:
+  - Select ```Debug/Deploy to local Windows```
+  - Leave ```Local Deploy Path``` blank
+  - Set the ```Mono Debug Port``` to the port in Godot --> Project --> Project Settings --> Mono --> Debugger Agent
+    - Also select ```Wait for Debugger``` in the Godot Mono options.  `This Godot Addon <https://godotengine.org/asset-library/asset/435>`_ may be helpful.
+5. Run the game in Godot. It should hang at the Godot splash screen while it waits for your debugger to attach.
+6. In VS2019, open your project and choose Extensions --> Mono --> Attach to Mono Debugger.