Add docstring

src/main/java/bdv/viewer/Interpolation.java

@@ -49,6 +49,13 @@ public enum Interpolation
 		return name;
 	}
 
+	/**
+	 *
+	 * @return The next {@link Interpolation} value in the order defined by
+	 * {@link Interpolation#values()} with cyclic continuation: The last element
+	 * returns the first element. Can be used to toggle/cycle through interpolations
+	 * in graphical user interface.
+	 */
 	public Interpolation next() {
 		return Interpolation.values()[ ( this.ordinal() + 1 ) % Interpolation.values().length ];
 	}