Support the Home key to return to the beginning of a help page

Currently when the Help Viewer is focused, I can use the Up/Down Arrow keys to scroll a line at a time, and I can use the Page Up/Page Down keys to scroll a page at a time.

I'd like to also use the Home key to scroll to the beginning of the document, but currently it has no effect.  For example, some Qt class documentation pages are dozens or hundreds of pages, so in order to (for example) view the class inheritance or member list at the top of the page, I currently need to either hold the Page Up key for many seconds, or move over to the mouse and drag the scroll bar.