While there is a page in Help for info("modifiers"), that page in not listed in the “See Also” section of the info( page. That list, afaict, is meant to include all variants of the info( function.
info("mouse") is also missing from the list. I did not check the whole list. I do not know if the list is meant to be exhaustive. I found the info("modifiers") page by searching for “modifier” after not turning it up on the info( page.
You could also just search for “info(” in the Help wizard.
Items appear in the See Also list according to the Tags that have been entered in the source code for the item. You can see this code by right-clicking in the big box at the top of the list and selecting Open Corrections Window …. Look in the line beginning with “<«Tags»>”.
Jim has clearly been extremely slack in failing to enter the correct tags in every info( entry and will no doubt be severely punished for this 