Monitoring doc was added

doc/monitoring/prometheus.md

@@ -0,0 +1,72 @@
+## Monitoring
+
+Instaclustr allows you scrap clusters metrics via its Monitoring API.
+
+If you use [Prometheus-Operator](https://github.com/prometheus-operator/prometheus-operator) as your monitoring system:
+
+There are two ways of configuring Prometheus to scrap Instaclustr metrics:
+1. By creating a configuration file and providing it to the Prometheus Operator by passing a secret with configuration of the job 
+
+    A template of the job config:
+    ```yaml
+    - job_name: instaclustr_prometheus
+      scheme: https
+      http_sd_configs:
+            - url: https://{ACCOUNT_ID}.prometheus.monitoring.dev.instaclustr.com/discovery/v1/
+              basic_auth:
+                #get from account settings page
+                username: {USERNAME}
+                password: {MONITORING_API_KEY}
+      metrics_path: 'metrics/v2/query'
+      basic_auth:
+        #get from account settings page
+        username: {USERNAME}
+        password: {MONITORING_API_KEY}
+    ```
+    
+    Creating a secret which contains the described config:
+    ```shell
+    kubectl create secret generic {your-secret-name} --from-file={your-config.yaml}
+    ```
+
+    By updating your prometheus with the following configuration will allow your prometheus to
+    scrap metrics of your clusters on Instaclustr:
+    ```yaml
+    # Your prometheus manifest
+      additionalScrapeConfigs:
+        name: {your-secret-name}
+        key: {your-config.yaml}
+    ```
+
+2. If your prometheus is deployed via Helm everything is getting easier.
+
+    In your `values.yaml` file which stores the configuration of the whole kube-prometheus-stack just add the following
+    settings to the configuration of prometheus:
+
+    ```yaml
+   additionalScrapeConfigs:
+    - job_name: instaclustr_prometheus
+      scheme: https
+      http_sd_configs:
+            - url: https://{ACCOUNT_ID}.prometheus.monitoring.dev.instaclustr.com/discovery/v1/
+              basic_auth:
+                #get from account settings page
+                username: {USERNAME}
+                password: {MONITORING_API_KEY}
+      metrics_path: 'metrics/v2/query'
+      basic_auth:
+        #get from account settings page
+        username: {USERNAME}
+        password: {MONITORING_API_KEY}
+      ```
+
+    It will create a secret which stores the following jobs configuration and provide it to the prometheus.
+
+If you want to scrap metrics from a specific cluster just provide its `clusterId` to the url:
+```yaml
+http_sd_configs:
+  - url: https://{ACCOUNT_ID}.prometheus.monitoring.dev.instaclustr.com/discovery/v1/{CLUSTER_ID}
+```
+
+If you want to read more about Instaclustr Metrics and configuring of Prometheus please 
+follow our [doc](https://www.instaclustr.com/support/api-integrations/integrations/instaclustr-monitoring-with-prometheus/).