Seems clear and useful. That said, there's nothing particularly bad or inaccessible about the actual Emacs Lisp manual: https://www.gnu.org/software/emacs/manual/html_mono/elisp.ht...
Or the official tutorial: https://www.gnu.org/software/emacs/manual/html_mono/eintr.ht... (which to be clear I haven't read, but have heard nice things about).
Of all the things for which emacs can be criticised, documentation rigor is really not one.
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