These are Windows .chm compiled HTML help files.
One is for the current version, the others are for (some of) the older versions.
When first downloaded, Windows systems may refuse to open the help file, showing "Navigation to the webpage was canceled!"; this is caused by a standard Windows security action; to enable viewing:
- Select the .chm file in Windows File Explorer.
- 'Right-click' to invoke the context menu.
- Select 'Properties' to invoke the Properties dialogue.
- Near the bottom of the 'General' tab will be a comment "This file came from another computer and might be blocked to help protect this computer".
- Next to the comment should be a button labelled 'Unblock'; click this button (assuming that you trust the compiled HTML help file to be benign).
- Exit from the dialogue using the 'OK' button.