is it appropriate for some content to be *only* in the reference guides?

  i was continuing my perusal of the docs and was going over the
sections related to creating a custom distro and distro features and,
in following a link to the reference manual variables glossary, i was
surprised to see a couple distro-related variables i had never seen
before (this one and the one immediately following):

https://docs.yoctoproject.org/ref-manual/variables.html#term-DISTRO_FEATURES_FILTER_NATIVE

i had never heard of these two variables, and i confirmed that they
are not mentioned *anywhere* in the regular docs (except in the
migration-2.3 guide). so how is a developer supposed to know about
these variables if they're not mentioned anywhere other than in the
reference manual?

rday