> What about adding the extended `symbol-class` function from Marginalia
> directly to help-fns.el? Note that the Marginalia function returns
> multiple characters "fv" if a symbol denotes both a function and a variable.
>
> Do you want to keep the `symbol-class` to be a single character under
> all circumstances?

I have tried to use marginalia--symbol-class for help--symbol-class,
and noticed a few problems:

1. It's hard to visually scan the column with types
   when the primary char (f, c, v, u) is not the first in the row.
   In the following patch I moved the primary char to the beginning.

2. Also it would help to see the letter of the primary char
   if secondary chars are not letters.  So I replaced "o" (obsolete)
   with a strikethrough symbol "-".

3. Are Unicode characters allowed?  Then could we add to the primary char
   e.g. COMBINING LONG STROKE OVERLAY (U+0336) to designate obsolete.

4. The remaining secondary letter is "l" for local, but I can't find
   a non-letter character to replace it.

5. Isn't using formatting such as "%-6s" not suitable in the backend?
   At least, I moved it out of help--symbol-class.  Ideally,
   the frontend should adjust column sizes to fit them to the longest value.

6. The format "%-6s " with 7 placeholders that is too wide for most symbols
   when a tiny fraction of symbols has 4 chars max, so reduced it to 4: