Update README.md to show usage examples

Signed-off-by: Raleigh Littles <[email protected]>

README.md

@@ -22,7 +22,31 @@ This is particularly useful if your device is out of reach or if the physical bu
 
 2. A "timesync" feature, allowing you to synchronize your geiger counter with your host PC's time. This is useful since these devices don't have any kind of NTP functionality.
 
-3. A CSV logging feature. This logs the geiger counter's readings directly to a CSV file, and is useful when you need to take long-running measurements that would exceed the geiger counter's on-device storage. (See `geiger_counter_log.csv` for an example of this file.)
+3. A CSV logging feature. This logs the geiger counter's readings directly to a CSV file, and is useful when you need to take long-running measurements that would exceed the geiger counter's on-device storage.
 
-4. A config dump feature. 🚧 This lets you see a parsed version of the device's configuration memory and take backups of it.
+![csv example](./docs/csv_screenshot.png)
 
+5. A config dump feature. 🚧 This lets you see a parsed version of the device's configuration memory and take backups of it.
+
+
+# Usage
+
+Run the binary providing the first and second arguments as the serial device name and baud rate, and then thirdly, the option you wish to use, e.g.:
+
+```bash
+$ ./gq_gmc /dev/ttyUSB0 115200 --gui
+```
+
+to launch the GUI
+
+```bash
+$ ./gq_gmc /dev/ttyUSB0 115200 --timesync
+```
+
+to do the time synchronization
+
+```bash
+$ ./gq_gmc /dev/ttyUSB0 115200 --log <CSV_FILENAME>
+```
+
+to store records to CSV file.