docs(bootstrap): correct marker_owned_by_self justification for current live_marker_owner semantics

Main's live_marker_owner has adopted self-owned markers since
160586ff8/dbc2a9c8e (#74761), so the cherry-picked comment's claim that
it 'maps self-ownership to None' is stale. The raw read is still the
right tool — the heal needs the single fact 'does the marker name our
PID' without age/liveness policy folded in.

apps/bootstrap-installer/src-tauri/src/update.rs

@@ -158,11 +158,13 @@ fn live_marker_owner(path: &Path) -> Option<MarkerOwner> {
 
 /// True when the on-disk marker names THIS process as its owner.
 ///
-/// `live_marker_owner` cannot answer this: it deliberately maps
-/// self-ownership to `None` (the #74761 pre-write adoption). The exit-2
-/// self-heal below needs the raw fact, because a `hermes update` child that
-/// refuses over OUR marker is a handoff-recognition failure, not a real
-/// concurrent update.
+/// A raw read is used instead of `live_marker_owner` on purpose: that
+/// helper folds in age and liveness policy (and, since the #74761
+/// adoption work, self-ownership handling has changed shape more than
+/// once). The exit-2 self-heal below needs exactly one raw fact — does
+/// the marker name our PID — because a `hermes update` child that
+/// refuses over OUR marker is a handoff-recognition failure in a stale
+/// checkout, not a real concurrent update.
 fn marker_owned_by_self(path: &Path) -> bool {
     std::fs::read_to_string(path)
         .ok()