Sunset project in favour of native GoBGP metrics

[SkalaNetworks]

I believe this project was created because the GoBGP maintainers weren't ok with integrating Prometheus directly into the codebase. This has changed for more than a year now and metrics are freely available directly from GoBGP.

This PR osrg/gobgp#2845 will add proper documentation for the metrics and ports some metrics from this project into GoBGP.

We should work on integrating more metrics directly into GoBGP as I think it is a better way to scrap metrics than relying on an external piece of software.

I propose this project be sunset and effort put directly onto GoBGP.

[SkalaNetworks]

@greenpau Tagging you as you own this repository and have created this cool exporter!

[greenpau]

@SkalaNetworks , yes. I am very much for it being archived. Doing it now.

[SkalaNetworks]

osrg/gobgp#2845 has been merged