Fix typo in examples/image.rs
prop*p*erties -> properties
// limitations under the License.
//! This showcase demonstrates how to use the image widget and is
-//! propperties. You can change the parameters in the GUI to see how
+//! properties. You can change the parameters in the GUI to see how
//! everything behaves.
// On Windows platform, don't show a console when opening the app.
