Fix/cortex export metric example

[redthor]

Just trying out https://aws.amazon.com/blogs/opensource/building-a-prometheus-remote-write-exporter-for-the-opentelemetry-go-sdk/ However, couldn't get docker-compose to run up successfully on Ubuntu.

One error:

/go.mod: no such file or directory

fixed with ab10ca0 - don't use Replace to a parent folder which is not mapped inside the container.

The other was with the use of host.docker.internal which is available on mac (and windows?) but not linux. This SO post to the rescue: https://stackoverflow.com/a/49149020

I couldn't use the 172.x.x.x address because it keeps changing. The qoomon/docker-host solution seems better.

[linux-foundation-easycla[bot]]

The committers are authorized under a signed CLA.

• :white_check_mark: Douglas Reith (ab10ca02d055a92214c630365f7ba370cba8a99b, 7b7ed74050d59fb8e62d7e5b84a3c2e84e49d4e6)

[MrAlias]

The cortex exporter and example were remove in https://github.com/open-telemetry/opentelemetry-go-contrib/releases/tag/v1.5.0