Tutorial references a now missing /health endpoint

[timsneath]

In the tutorial, there's a reference to a /health endpoint that is created in the buildRouter() method:

hummingbird-docs/Hummingbird.docc/Tutorials/Todos/Todos-1-Template.tutorial

Line 43 in ec8121c

Here we create the `Router`. We add a logging middleware to it (this logs all requests to the router). The function uses a result builder to create a stack of middleware, but you can also use `Router.add(middleware:)` to add individual middleware. Finally we add a single endpoint GET `/health` which returns a 200 (Ok) response.

However, the current template instead just creates a root endpoint:

https://github.com/hummingbird-project/template/blob/13e946207648d27f8b4c4091f4030d5a6a9e63be/Sources/App/Application%2Bbuild.swift#L41-L54

Accordingly, the tutorial should be updated to remove references to the /health endpoint.