Add docs for architecture-specific folders

Author: glopesdev

runtimes/README.md

@@ -1,3 +1,65 @@
 # Runtime Identifier Dependencies
 
-The NuGet package for the C# bindings includes binary distributions for major platform runtimes targeted by [liblsl](https://github.com/sccn/liblsl). To successfully build the package, these binaries need to be downloaded from [liblsl releases](https://github.com/sccn/liblsl/releases) and included in this folder following the RID naming conventions outlined in the [RID Catalog](https://docs.microsoft.com/en-us/dotnet/core/rid-catalog).
+The NuGet package for the C# bindings includes binary distributions for major platform runtimes targeted by [liblsl](https://github.com/sccn/liblsl). To successfully build the package, these binaries need to be downloaded from [liblsl releases](https://github.com/sccn/liblsl/releases) and included in this folder following the RID naming conventions outlined in the [RID Catalog](https://docs.microsoft.com/en-us/dotnet/core/rid-catalog).
+
+The following [architecture-specific folders](https://docs.microsoft.com/en-us/nuget/create-packages/supporting-multiple-target-frameworks#architecture-specific-folders) are recommended:
+
+```
+\runtimes
+    \linux-x64
+        \native
+            liblsl.so
+            liblsl.so.1.14.0
+    \osx-x64
+        \native
+            liblsl.dylib
+            liblsl.1.14.0.dylib
+    \win-x64
+        \native
+            lsl.dll
+    \win-x86
+        \native
+            lsl.dll
+```
+
+## Project files for dependent projects
+
+From Visual Studio 2019, both .NET Core (`dotnet`) and .NET Framework compilers will use the `RuntimeIdentifier` element of the new SDK csproj format to control which native dependencies to deploy to the final output folder.
+
+### .NET Core
+In .NET Core, the default is to generate cross-platform deployments, which means that all the runtimes will be deployed to the final output folder. By inserting a specific `RuntimeIdentifier` a build targeting only the specified architecture is generated.
+
+```xml
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net5.0</TargetFramework>
+    <!--<RuntimeIdentifier>linux-x64</RuntimeIdentifier>-->
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="lsl_csharp" Version="2.0.0" />
+  </ItemGroup>
+
+</Project>
+```
+
+### .NET Framework
+In legacy .NET framework projects, `RuntimeIdentifier` defaults to `win7-x86` which has the generic fallback to `win-x86`. Therefore, the above folder structure will automatically copy `lsl.dll` into the output folder of .NET Framework projects.
+
+```xml
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net472</TargetFramework>
+    <!--<RuntimeIdentifier>win-x64</RuntimeIdentifier>-->
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="lsl_csharp" Version="2.0.0" />
+  </ItemGroup>
+
+</Project>
+```