Alist of symbols already found in current apropos run.
Each element has the form
(SYMBOL SCORE FUN-DOC VAR-DOC PLIST WIDGET-DOC FACE-DOC CUS-GROUP-DOC)
where SYMBOL is the symbol name, SCORE is its relevance score (a
number), FUN-DOC is the function docstring, VAR-DOC is the
variable docstring, PLIST is the list of the symbols names in the
property list, WIDGET-DOC is the widget docstring, FACE-DOC is
the face docstring, and CUS-GROUP-DOC is the custom group
docstring. Each docstring is either nil or a string.