Initial version of autometrics-go

First version

This release of autometrics-go marks the first point where both main features of autometrics are implemented:

• Documentation link generation to Prometheus graphs is implemented, and
• Automatic alert generation for Prometheus is implemented.

Both happen solely from:

• adding a go:generate call for Autometrics, and
• annotating the functions with an autometrics:doc directive, that optionally takes arguments to add the alert
  generation part.

Demo

The example in the examples/web subfolder is the main source to learn about usage of autometrics.