meson: Fix docs installation when built as a subproject
This is yet another instance of Meson calling Ninja from the root project's build directory, which mucks with the output of custom_target.
Due to an influx of spam, we have had to impose restrictions on new accounts. Please see this wiki page for instructions on how to get full permissions. Sorry for the inconvenience.
This is yet another instance of Meson calling Ninja from the root project's build directory, which mucks with the output of custom_target.