Improve documentation on how to install a GWF I/O library on various platforms

Inspired by https://git.ligo.org/computing/helpdesk/-/issues/2919 (LIGO.ORG login required) we should improve the documentation of the optional extra libraries required for I/O with GWF.

Currently the docs just say

https://github.com/gwpy/gwpy/blob/46ebb08d51f5c44116f60591947cca04216b8fea/docs/timeseries/io.rst#L108-L113

with no detail on how to install those tools.