Add README for config package

pkg/config/README.md

@@ -0,0 +1,50 @@
+### Config Package
+
+#### Overview
+The `config` package manages configurations in Go applications,
+ensuring compatibility between `config.yaml` and `setup.env`. 
+`setup.env` is used to setup environment variables.
+
+Note - When both environment variables and config.yaml settings are present,
+the package prioritizes environment variables, overriding equivalent settings in config.yaml.
+
+#### Compatible configurations example
+
+The below configurations are compatible in this project.
+
+- `setup.env` contains:
+    ```
+    export LOGFILE_PATH=cm-beetle.log
+    ```
+
+- `config.yaml` has:
+    ```yaml
+    logfile:
+        path: ./cm-beetle.log
+    ```
+
+#### How to use it
+
+- Use a blank import in your package (e.g., main, logger, and so on)
+- Get a value using Viper
+
+Note - It's just my preference. `config.Init()` can be used.
+
+```go
+import (
+    // other packages
+
+    // Loads configurations from setup.env and config.yaml
+    _ "github.com/cloud-barista/cm-beetle/pkg/config"
+)
+
+func main() {
+    logFilePath := viper.GetString("logfile.path")
+    // Application logic follows
+}
+```
+
+#### Wrapping Up
+
+This setup illustrates the package's ability to harmonize settings from both `setup.env` and `config.yaml`,
+showcasing its versatility and ease of use.