When we try to get the doc of a erlang function we got

h :file.write
...
Module was compiled without docs. Showing only specs.

We need to use at least OTP 23 and have the dependencies to build the documentation.

On ubuntu

sudo apt-get install xsltproc fop
KERL_BUILD_DOCS=yes asdf install erlang 23.3.3
asdf local erlang 23.3.3
iex
h :file.write
Success doc is here !