Use consistent keywords for the `Module` class in C# code examples

[gefjon]

Reported on Discord.

Various C# module code examples in our Docs use different sets of keywords to define the Module class that holds all the module code. Apparently the RLS reference uses public partial class, and the C# reference has both static partial class and public static partial class.

Pick one set of keywords, put it in the style guide, then grep the docs for class Module and make every occurrence use exactly that set of keywords.