> https://i.imgur.com/Cv67yUN.png

FWIW -

I'm in favor of having top-level summary help for a
feature - help that's organized into groups such as
what you've now proposed for `help-for-help' (aka
`C-h C-h').

I've long done that for some of my libraries, using
such organized Help as mode help (`C-h m').

And I've used such organization for `C-h C-h' at
least since 1999, with minor updates - see attached
screenshot.

I've also added links on key descriptions.  I think
they help a lot.  I'm not in favor of just coloring
keys as you've proposed, as I've said before - it's
better to link them to their full help, IMO.

Yes, one can do what the `C-h C-h' instructions say:
"type a help option...".

But you can also click key-description links to get
full help on a key.  IOW, the display is part of a
dialog, yes, but you can also use it like an ordinary
*Help* buffer.

Just what organization should be used is a separate
question.  What I wanted to say is: 

1. I agree that grouping helps.
2. I've long done that for `C-h C-h'.
3. I propose help links on keys (not just action-less
   colored text).

Here's a plain text version of what the screenshot shows:
_____

This is the Emacs ‘help-command’, accessible via ‘C-h’.
Type a help option (below) now, for help on a particular topic.
Use ‘SPC’ or ‘DEL’ to scroll this text.  Type ‘q’ to exit Help.
(A "command" is any function that you can execute via ‘M-x’.)

LEARNING EMACS
--------------
t:   Start a tutorial for learning Emacs.
C-f: Explain frequently asked Emacs questions.

COMMONLY USED
-------------
RET: Help about a key sequence or something you click with the mouse.
a:   Show commands that match a regular expression (regexp).
b:   Show current key bindings: keyboard, menu bar, and mouse.
c:   Show the doc for an Emacs command.
f:   Show the doc for an Emacs function.
F:   Open the Emacs manual for an Emacs command.
i:   Enter ‘Info’, to browse manuals, including Emacs and Emacs Lisp.
k:   Describes the command bound to keyboard/menu/mouse sequence.
K:   Open the Emacs manual for a keyboard/menu/mouse sequence.
m:   Describe the current major and minor modes.
o:   Show an Emacs user option’s value and documentation.
v:   Show an Emacs variable’s value and documentation.

MORE ADVANCED HELP
------------------
d:   Show Emacs functions and variables whose doc matches a regexp.
l:   Show what you just typed (last 100 keystrokes & mouse actions).
n:   Describe what’s new in this Emacs release.
p:   Find Emacs-Lisp libraries that match a topic.
s:   Describe the current syntax table.
S:   Find a symbol in the manual for the current buffer’s language.
u:   Find a topic in the Unix manual.
w:   Identify a keyboard/menu/mouse sequence that invokes a command.
C-a: Show Emacs functions and variables that match a regexp.
C-c: Identify the command bound to a keyboard/menu/mouse sequence.
C-l: Show the path name to an Emacs library.
C-o: Show value and doc for an Emacs user option of a given type.
M-o: Pop to Help buffer or back to the buffer that sent you to Help.
C-M-a: Show the tags matched by a given string.
g:   Show information about the GNU project.
C-w: Show information about the absence of a warranty.
M-c: Show the GNU Emacs General Public License.
M-x describe-distribution: Show Emacs ordering information.

INTERNATIONAL
-------------
C:   Describe a coding system.
h    Display the HELLO file, which illustrates scripts and languages.
I:   Describe an input method.
L:   Describe a language environment.
_____


> (Type SPC or DEL to scroll, or q to exit.)
> 
> Getting Help
> 
>    m	Help for current minor and major modes and their commands
>    b	Show all key bindings
>    k	Show help for key
>    c	Show help for key briefly
>    w	Show which key runs a given command
> 
>    a	Search for commands (see also M-x apropos)
>    d	Search documentation of functions, variables, and other items
>    f	Show help for function
>    o	Show help for function or variable
>    v	Show help for variable
> 
> Info Manuals
> 
>    r	Show Emacs manual
>    F	Show Emacs manual section for command
>    K	Show Emacs manual section for command bound to key
>    i	Show all included manuals
>    R	Show given manual
>    S	Find symbol in Info manual for current programming language
> 
> Misc Help
> 
>    p	Search for packages matching topic
>    P	Describe Emacs Lisp package
>    e	Show recent messages
>    g	Show information about the GNU project
>    l	Show last 300 input keystrokes (lossage)
>    s	Show current syntax table
>    .	Show local help at point
>    t	Start the Emacs tutorial
> 
> Help Files
> 
>    C-a	About Emacs
>    C-c	Emacs copying permission (GNU General Public License)
>    C-d	Debugging GNU Emacs
>    C-e	External packages
>    C-f	Emacs FAQ
>    C-m	Order printed Emacs manuals
>    C-n	News of recent Emacs changes
>    C-o	Emacs ordering and distribution information
>    C-p	Known Emacs problems
>    C-t	Emacs TODO
>    C-w	Information on absence of warranty for GNU Emacs
> 
> Language Help
> 
>    C	Describe coding system
>    I	Describe input method
>    L	Describe language environment
>    h	Display the HELLO file illustrating various scripts