Turns out search engines were likely to lead #Guile users to the manual of 1.6, 1.8 (both unmaintained for 15+ years), or 2.9.9 (a pre-release of 3.0), all of which were lingering under gnu.org/software/guile/docs.

After a discussion on IRC, I cleaned it up. Now https://gnu.org/s/guile/learn/ only links to up-to-date material.