When using the functionality
SPC h f to describe a function, then for example
face-spec-set, this will open a pop-up buffer in helpful mode. Then navigating to one of the links in the document, e.g.
RETURN opens a new helpful-mode document describing
defface. There is no way to go back to the first page.
There is an issue and a pull request related to adding this functionality in
helpful, but the repository is nearly inactive.
Doom is using
advice-add to override the default
help-mode to use
help-mode does have the ability to navigate back using
C-c C-b, but
helpful-mode does not. This makes navigating the documentation very hard.