Add tooltip for new option

The URL hints feature is enabled by setting a modifier key combination. In the second screenshot (Advanced tab of the Profile settings: konsole-hints-rev-option), it's set to Control+Alt. When the configured key combination is held, any URLs in the current view of the Konsole window are highlighted and numbered, starting with 1 for the topmost URL down to 9. If there are more than 9 URLs, the bottom-most ones are not numbered (as seen in the first screenshot: konsole-hints-before). Pressing a number while the hints are highlighted opens the corresponding URL in the default web browser.