Update docs

[sed-i]

Currently, alertmanager docs on charmhub have the following structure:

• Overview (taken from README.md)
• Docs - Overview
• Configuration
• Clustering
• Relations

All of the above, except Relations, is already incorporated in the README.md file.
I think the Relations doc can be entirely incorporated in metadata.yaml.

Fixes #109.

[Abuelodelanada]

Why do you think the Relations doc can be omitted entirely?

Right now in Prometheus we already have Relations in README.md. From my point of view, we should have a a standardised way to write the README.md

Can we remove from this PR the modifications in charm.py and tests and create another PR with that?

[sed-i]

Why do you think the Relations doc can be omitted entirely?

Bad phrasing on my part. Rephrased.

Right now in Prometheus we already have Relations in README.md.

After trimming down all the superfluous "any charm with X relation over the Y interface" statements, I wasn't left with much. Whatever left I moved into metadata.yaml.

From my point of view, we should have a a standardised way to write the README.md

Agreed. I'm proposing to describe relations in-context (inside metadata.yaml).

Can we remove from this PR the modifications in charm.py and tests and create another PR with that?

Good point. Split into #114