Host a template repository within the "tower-lsp" organization

[mrnossiom]

Looking at IWANABETHATGUY/tower-lsp-boilerplate#7, it seems that many people are interested in a tower-lsp template.

[mrnossiom]

We could also update https://github.com/silvanshade/tower-lsp-web-demo and host it in the org.
And update the examples/wasm/README.md accordingly.