/usr/share/doc/libpxp-ocaml-dev/html/api is in libpxp-ocaml-dev 1.2.4-1build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libpxp-ocaml-dev/html/ref
/usr/share/doc/libpxp-ocaml-dev/html/ref