docs: Manual - Visual Studio extension

[VaclavElias]

We should add more content https://doc.stride3d.net/latest/en/manual/get-started/visual-studio-extension.html

Including, this feature which might be unknown for others. The extension also adds this to VS.

[Doprez]

Some of the features that I know about for this extension:

• Provides Syntax highlighting for SDSL and SDFX files
• Automatically creates shader key files for users to change shader value programmatically
  The other 3 are in the picture above

Alternatives:

• HLSL plugin for VSCode works for syntax highlighting and autocomplete as long as you add SDSL files to be scanned by the plugin through the VSCode settings. This still does not create the Shaderkey files automatically but user can do it manually if they want to.

• I assume Rider has the same thing? Haven't tried myself though.

[VaclavElias]

Thanks for adding some content 👍.