docs(tvix/docs): add document about drvPath differences r/6510

This question popped up every once in a while. While already explained
quite well at
https://inbox.tvl.su/depot/20230316120039.j4fkp3puzrtbjcpi@tp/T/#t,
it's not easily accessible.

Lift it from there into tvix/docs for better visibility.

Change-Id: I5f2d4aff31ab4adc421e06a7d36c871f45e09100
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9080
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Tested-by: BuildkiteCI

0 files changed, 0 insertions, 0 deletions