README: Add simple example

README.md

@@ -27,6 +27,21 @@ python setup.py install
 ```
 
 
+# Example
+
+```python
+from openocd import OpenOcd
+
+with OpenOcd() as oocd:
+    oocd.halt()
+    registers = oocd.read_registers(['pc', 'sp'])
+
+    print('Program counter: 0x%x' % registers['pc'])
+    print('Stack pointer: 0x%x' % registers['sp'])
+
+    oocd.resume()
+```
+
 # License
 
 This project is licensed under the [GPLv3+](https://www.gnu.org/licenses/gpl-3.0.en.html) - see the [LICENSE](LICENSE) file for details.