Add Detailed README Documentation for using-cron-jobs Example in GoFr (#2164)

Author: Joystonm

examples/using-cron-jobs/Readme.md

@@ -0,0 +1,98 @@
+# Using Cron Jobs in GoFr
+
+This example demonstrates how to schedule and run background jobs using the **GoFr** framework’s built-in Cron Job support.
+
+---
+
+## Overview
+
+In this example, we:
+
+* Schedule a job named `counter` to run **every second**.
+* Increment a counter on each execution and log its value.
+* Run the application for a limited duration (3 seconds) to demonstrate the cron execution in action.
+* Include a unit test to verify that the cron job executes successfully.
+
+---
+
+## How to Run
+
+1. **Clone the repository** and navigate to this example:
+
+   ```bash
+   git clone https://github.com/gofr-dev/gofr.git
+   cd gofr/examples/using-cron-jobs
+   ```
+
+2. **Run the application**:
+
+   ```bash
+   go run main.go
+   ```
+
+   * The counter will increment every second.
+   * Application will stop automatically after 3 seconds.
+     *(In a real-world application, you would call `app.Run()` to keep the cron running indefinitely.)*
+
+---
+
+## How It Works
+
+### main.go
+
+```go
+app.AddCronJob("* * * * * *", "counter", count)
+```
+
+* Schedules the `count` function to run every second.
+* Cron syntax here uses six fields (including seconds) — `"* * * * * *"` means “every second.”
+
+```go
+time.Sleep(duration * time.Second)
+```
+
+* Stops the application after the `duration` (3 seconds) for demonstration purposes.
+
+### count Function
+
+* Acquires a write lock.
+* Increments the counter variable `n`.
+* Logs the current counter value.
+
+---
+
+## Testing
+
+The test (`main_test.go`):
+
+* Runs the `main()` function.
+* Waits slightly longer than 1 second.
+* Checks if the counter has incremented exactly once.
+* Logs the metrics server host.
+
+Run the test:
+
+```bash
+go test -v
+```
+
+Expected output:
+
+```
+=== RUN   Test_UserPurgeCron
+--- PASS: Test_UserPurgeCron (1.10s)
+PASS
+```
+
+---
+
+## Example Output
+
+When running `main.go`, you should see:
+
+```
+INFO    Count: 1
+INFO    Count: 2
+INFO    Count: 3
+```
+