[feature request] A new cookie type [!] showing the last note taken

[Ihor Radchenko]

Over the years of using Org I often have a need to add a short note
about how to proceed with some task:

***** REVIEW check again, subscribe | sindresorhus/awesome: 😎 Awesome lists 
about all kinds of interesting topics :BOOKMARK:
:PROPERTIES:
:CREATED: [2020-03-15 Sun 18:59]
:Source: https://github.com/sindresorhus/awesome
:END:
:LOGBOOK:
CLOCK: [2020-03-17 Tue 16:18]--[2020-03-17 Tue 17:46] =>  1:28
CLOCK: [2020-03-17 Tue 16:03]--[2020-03-17 Tue 16:18] =>  0:15
- Refiled on [2020-03-16 Mon 23:59]
:END:

In the above example, the short note is "check again, subscribe".
The note is not fixed, but changes as I progress with completing the
task.

This is even more useful for delegated or HOLD tasks where I often need
to add a short note why the task is delegated or put on hold:

** HOLD Finish the text prop org-mode | make babel support org file links in 
header args (:file or :dir) 
[[id:468e0645-68aa-4e14-86de-e5ce153538e3][[2017-09-22 Fri] 
CuNbARBshearstrength]] :HOLD:
:PROPERTIES:
:CREATED: [2020-07-20 Mon 16:53]
:SHOWFROMDATE: 2020-08-15
:END:
:LOGBOOK:
- State "HOLD"       from "NEXT"          [2020-08-10 Mon 15:16] \\
  Finish the text prop org-mode
- Refiled on [2020-07-20 Mon 17:15]
CLOCK: [2020-07-20 Mon 16:53]--[2020-07-20 Mon 16:54] =>  0:01
:END:

Seeing this note directly in the headline without a need to dig into the
task body / LOGBOOK drawer is really handy.

In this last example, I had to duplicate the note taken using built-in
note mechanism into headline, which was inconvenient. It would be handy
if I could simply add a [!] cookie (similar to [/] or [%] cookies) to
the headline to show the last note taken for this task. Then, I could
easily see the reason why the task is blocked or what I am supposed to
do with the task right in agenda view or in the folded headline.
Something like the following

** HOLD [!] make babel support org... :HOLD:
:LOGBOOK:
- State "HOLD"       from "NEXT"          [2020-08-10 Mon 15:16] \\
  Finish the text prop org-mode
- Refiled on [2020-07-20 Mon 17:15]
CLOCK: [2020-07-20 Mon 16:53]--[2020-07-20 Mon 16:54] =>  0:01
:END:

The cookie would be replaced by the last note text, according to
user-defined format (say, "[%s] |"):

** HOLD [Finish the text prop org-mode] | make babel support org... :HOLD:
:LOGBOOK:
- State "HOLD"       from "NEXT"          [2020-08-10 Mon 15:16] \\
  Finish the text prop org-mode
- Refiled on [2020-07-20 Mon 17:15]
CLOCK: [2020-07-20 Mon 16:53]--[2020-07-20 Mon 16:54] =>  0:01
:END:

What do you think?

Best,
Ihor