chore(matrix_alertmanager): rename role to follow ansible galaxy naming conventions

roles/matrix_alertmanager/README.md

@@ -0,0 +1,20 @@
+# `finallycoffee.observability.matrix-alertmanager` ansible role
+
+## Overview
+
+Runs [matrix-alertmanager](https://github.com/jaywink/matrix-alertmanager)
+in a docker container, and bridges alerts from alertmanager
+into a configured matrix room (per configured receiver).
+
+## Configuration
+
+### Required configuration
+
+The following variables need to be defined in order for `matrix-alertmanager` to
+be able to work:
+
+- `matrix_alertmanager_secret`: The secret configured in alertmanager for this receiver
+- `matrix_alertmanager_homeserver_url`: URL to the homeserver to log in to, including scheme and port.
+- `matrix_alertmanager_mxid`: The matrix ID in the form `@local:server.tld` to use
+- `matrix_alertmanager_access_token`: The matrix access token for `matrix_alertmanager_mxid` (Note: this is not the password)
+- `matrix_alertmanager_rooms`: A list of objects `{ name, room_id }` where `name` is the receiver name in alertmanager and `room_id` is a matrix room ID (not an alias)