Improve documentation

README.md

@@ -20,7 +20,7 @@ Before using `inspector` you need to have [kubectl](https://kubernetes.io/docs/t
    go install github.com/qba73/inspector/cmd/inspector@latest
    ```
 
-1) Run it:
+1) Get help:
 
    ```shell
    inspector -h
@@ -36,6 +36,18 @@ Before using `inspector` you need to have [kubectl](https://kubernetes.io/docs/t
    In verbose mode (-v), prints out progess, steps and all data points to stdout.
    ```
 
+1) Collect data points from `default` namespace
+
+   ```shell
+   inspector -n default > default.json
+   ```
+
+1) Collect data points from `nginx-ingress` namespace
+
+   ```shell
+   inspector -n nginx-ingress > nginx-ingress.json
+   ```
+
 ### How to install it and use as a `kubectl` plugin
 
 1) Clone the repo.
@@ -75,6 +87,20 @@ Before using `inspector` you need to have [kubectl](https://kubernetes.io/docs/t
    In verbose mode (-v), prints out progess, steps and all data points to stdout.
    ```
 
+1) Collect data points from `default` namespace
+
+   Note that `inspector`'s default namespace is `default`.
+
+   ```shell
+   inspector > default.json
+   ```
+
+1) Collect data points from `nginx-ingress` namespace
+
+   ```shell
+   inspector -n nginx-ingress > nginx-ingress.json
+   ```
+
 ## How it works
 
 The program collects K8s cluster and [NGINX Ingress Controller](https://kubernetes.io/docs/concepts/services-networking/ingress/) diagnostics data. It prints out data in the JSON format to the stdout. This allows the output to be piped to other tools (for example [jq](https://jqlang.github.io/jq/)) for further parsing and processing.