Docs: Refactor alerting documentation (part 1) (#48664)

* Initial commit

* Moved files, ad fixed broken relrefs.

* Fixed other broken relrefs

* More changes.

* Fixing broken relrefs

* More changes.

* Fixed last of the broken links

* More re-org.

* Added aliases and some weight adjustments

* More aliases.

* Fix fundamentals topic.

* Fixed remaining metadata issues

* Ran prettier

docs/sources/alerting/alerting-rules/create-mimir-loki-managed-rule.md

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+title = "Create Grafana Mimir or Loki managed alert rule"
+description = "Create Grafana Mimir or Loki managed alerting rule"
+keywords = ["grafana", "alerting", "guide", "rules", "create"]
+aliases = ["/docs/grafana/latest/alerting/unified-alerting/alerting-rules/create-cortex-loki-managed-recording-rule/", "/docs/grafana/latest/alerting/unified-alerting/alerting-rules/create-mimir-loki-managed-recording-rule/"]
+weight = 400
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+
+# Create a Grafana Mimir or Loki managed alerting rule
+
+Grafana allows you to create alerting rules for an external Grafana Mimir or Loki instance.
+
+## Before you begin
+
+- Verify that you have write permission to the Prometheus data source. Otherwise, you will not be able to create or update Grafana Mimir managed alerting rules.
+
+- For Grafana Mimir and Loki data sources, enable the ruler API by configuring their respective services.
+
+  - **Loki** - The `local` rule storage type, default for the Loki data source, supports only viewing of rules. To edit rules, configure one of the other rule storage types.
+
+  - **Grafana Mimir** - use the [legacy `/api/prom` prefix](https://grafana.com/docs/mimir/latest/operators-guide/reference-http-api/#path-prefixes), not `/prometheus`. The Prometheus data source supports both Grafana Mimir and Prometheus, and Grafana expects that both the [Query API](https://grafana.com/docs/mimir/latest/operators-guide/reference-http-api/#querier--query-frontend) and [Ruler API](https://grafana.com/docs/mimir/latest/operators-guide/reference-http-api/#ruler) are under the same URL. You cannot provide a separate URL for the Ruler API.
+
+> **Note:** If you do not want to manage alerting rules for a particular Loki or Prometheus data source, go to its settings and clear the **Manage alerts via Alerting UI** checkbox.
+
+## Add a Grafana Mimir or Loki managed alerting rule
+
+1. In the Grafana menu, click the **Alerting** (bell) icon to open the Alerting page listing existing alerts.
+1. Click **New alert rule**.
+1. In Step 1, add the rule name, type, and storage location.
+   - In **Rule name**, add a descriptive name. This name is displayed in the alert rule list. It is also the `alertname` label for every alert instance that is created from this rule.
+   - From the **Rule type** drop-down, select **Mimir / Loki managed alert**.
+   - From the **Select data source** drop-down, select an external Prometheus, an external Loki, or a Grafana Cloud data source.
+   - From the **Namespace** drop-down, select an existing rule namespace. Otherwise, click **Add new** and enter a name to create a new one. Namespaces can contain one or more rule groups and only have an organizational purpose. For more information, see [Grafana Mimir or Loki rule groups and namespaces]({{< relref "./edit-mimir-loki-namespace-group.md" >}}).
+   - From the **Group** drop-down, select an existing group within the selected namespace. Otherwise, click **Add new** and enter a name to create a new one. Newly created rules are appended to the end of the group. Rules within a group are run sequentially at a regular interval, with the same evaluation time.
+     {{< figure src="/static/img/docs/alerting/unified/rule-edit-mimir-alert-type-8-0.png" max-width="550px" caption="Alert details" >}}
+1. In Step 2, add the query to evaluate.
+   - Enter a PromQL or LogQL expression. The rule fires if the evaluation result has at least one series with a value that is greater than 0. An alert is created for each series.
+     {{< figure src="/static/img/docs/alerting/unified/rule-edit-mimir-query-8-0.png" max-width="550px" caption="Alert details" >}}
+1. In Step 3, add conditions.
+   - In the **For** text box, specify the duration for which the condition must be true before an alert fires. If you specify `5m`, the condition must be true for 5 minutes before the alert fires.
+     > **Note:** Once a condition is met, the alert goes into the `Pending` state. If the condition remains active for the duration specified, the alert transitions to the `Firing` state, else it reverts to the `Normal` state.
+1. In Step 4, add additional metadata associated with the rule.
+   - Add a description and summary to customize alert messages. Use the guidelines in [Annotations and labels for alerting]({{< relref "./alert-annotation-label.md" >}}).
+   - Add Runbook URL, panel, dashboard, and alert IDs.
+   - Add custom labels.
+1. To evaluate the rule and see what alerts it would produce, click **Preview alerts**. It will display a list of alerts with state and value of for each one.
+1. Click **Save** to save the rule or **Save and exit** to save the rule and go back to the Alerting page.