Fix monitoring & telemetry docs

[shaaza]

1. The BetterStack integration section should repeat "Step 1: Enable the OpenTelemetry Exporter" of the Getting Started, but as an optional step since it is only required when the users want to emit custom metrics and logs in addition to the default CPU, network, and memory metrics.

2. After the Step 1 has been done, the banner "To redeploy, select your latest deployment in the Shuttle Console and click “Redeploy”." is wrong. Redeploy via the console redeploys the same commit. We should ask the user to redeploy via the CLI if there have been any code changes, and via the console, if there has been no code changes.

Having two separate modalities is confusing for most users and affects onboarding on to the feature (i.e. 'if you want custom metrics, you need code change + deployment, but if you want only default CPU + Network + Mem metrics, you can just redeploy via console'). Instead, let's assume we want most users to use custom metrics and write the docs for that.