Move Wasmtime for .NET to the Wasmtime repo.

This moves the Wasmtime for .NET implementation to the Wasmtime repo.

Wasmtime for .NET is a binding of the Wasmtime API for use in .NET.

crates/misc/dotnet/docs/toc.yml

@@ -0,0 +1,7 @@
+- name: Articles
+  href: articles/
+- name: API Documentation
+  href: api/
+  homepage: api/index.md
+- name: GitHub Repo
+  href: https://github.com/bytecodealliance/wasmtime