doc,net: reword Unix domain path paragraph in net.md

Reword the paragraph on Unix domain paths. Hopefully, it is a little bit
more clear and easier to read now.

PR-URL: https://github.com/nodejs/node/pull/31684


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>