There are a couple of options for this, to me the easiest way is grouping templates using the built-in mechanism.
My way to use capture templates is based in memory muscle rather than digging a long menu, so how the menu is displayed should be concise in case I don't recall what key was for something. I do call capture using F12, then if I want to insert a note I'll use n and, let's say b if it's about a book.
So, to achieve this if you look for org-capture-templates documentation:
keys The keys that will select the template, as a string, characters
only, for example "a" for a template to be selected with a
single key, or "bt" for selection with two keys. When using
several keys, keys using the same prefix key must be together
in the list and preceded by a 2-element entry explaining the
prefix key, for example
("b" "Templates for marking stuff to buy") ```
meaning that you can use n to group notes as heading and using two chars keys nb, nm, nw, na for books, miscelanea, work and articles - you should also follow the other conditions.
So something like this in your template definition:
("n" "Notes")
("nb" "Notes about books" <your template definition here>)
("nm" "Misc notes" <your template definition here>)
("nw" "Work notes" <your template definition here>)
("na" "Notes about articles" <your template definition here>)
Will give you a n submenu which unfolds in a new menu once pressed. Calling capture templates will look like this:
... <other capture templates>
[b] Books to read
[n]... Notes
... <other capture templates>
and pressing n will lead to:
n [b] Notes about books
n [m] Misc notes
n [w] Work notes
n [a] Notes about articles
You can do it in your init file or using customize interface. Of course there is more about this in the documentation.