Add .NET core/5/6 compiling instructions

CLI/MCGalaxyCLI_core.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <TargetFramework>net6.0</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>

README.md

@@ -66,7 +66,7 @@ Click **Settings** in the MCGalaxy window, then tick the **Public** checkbox. Th
 
 This makes your server appear in the server list on classicube.net and in the ClassiCube client.
 
-Compiling
+Compiling - mono and .NET framework
 -----------------
 **With an IDE:**
 * Visual Studio : Open `MCGalaxy.sln`, click `Build` in the menubar, then click `Build Solution`. (Or press F6)
@@ -77,6 +77,18 @@ Compiling
 * Modern mono: Type `msbuild MCGalaxy.sln` into Terminal
 * Older mono: Type `xbuild MCGalaxy.sln` into Terminal
 
+Compiling - .NET 6 / .NET 5 / .NET Core
+-----------------
+**Command line:**
+
+* Compiling for .NET 6: No changes necessary
+* Compiling for .NET 5: Change `TargetFramework` in CLI/MCGalaxyCLI_Core.csproj to `net5.0`
+* Compiling for .NET Core: Change `TargetFramework` in CLI/MCGalaxyCLI_Core.csproj to `netcoreapp3.1`
+
+Then navigate into `CLI` directory, and then run `dotnet build MCGalaxyCLI_Core.csproj`
+
+**You will also need to copy `libsqlite3.so.0` from system libraries to `libsqlite3.so` in the server folder**
+
 Copyright/License
 -----------------
 See LICENSE for MCGalaxy license, and license.txt for code used from other software.