fix(qbittorrent): the comment warning about doubled dollars contained one

The new flux-postbuild-substitution guard failed the merge on
apps/wave-0/qbittorrent.yaml:155 — a run of two dollars in a substituted
path that nothing justifies. It was inside the postStart hook's own comment
EXPLAINING the hazard: prose about what envsubst does to a doubled dollar,
written with a literal doubled dollar.

Functionally harmless — it is a bash comment, and collapsing it changes no
behaviour — but the guard cannot distinguish a comment from content that
reaches the workload, and it is right not to try: that is precisely how the
nextcloud-db break slipped through. Reworded in words instead.

Worth recording that this is the second time today the same trap caught an
explanation of itself: my own fix for the nextcloud-db incident (16b7fcd)
also shipped dollars inside the comment describing the danger, and I only
caught it because I re-read the file. This time the guard caught it, on work
merged minutes earlier — which is the guard earning its place.

Re-rendered so the golden matches the catalog.

Co-Authored-By: Claude Opus 5 <[email protected]>

catalog/qbittorrent.yaml

@@ -127,7 +127,7 @@ lifecycle:
           # CLUSTER — but only there:
           # envsubst collapses the doubled dollar, so the SAME text run any other way (a `kubectl
           # apply` of the golden, which runs no envsubst; a hand `kubectl exec` of the script during
-          # development) keeps `$$`, which bash expands to its own PID. That is not a hypothetical;
+          # development) keeps the doubled dollar, which bash reads as its own PID. Not hypothetical;
           # see the PORT comment below for the bug it actually caused here. Bare `$VAR` and `$(cmd)`
           # are untouched by envsubst, so they are used throughout and the script behaves IDENTICALLY
           # however it is run.