Change docs to refer to "currently configured time zone"

The "timezone of an instant" is a misnomer because the `instant` type
doesn't carry timezone information. The host has a currently configured
time zone (or has no such concept, in which case the only sensible thing
to do is use UTC).

Author: ptomato

wit-0.3.0-draft/timezone.wit

@@ -5,11 +5,11 @@ interface timezone {
     @unstable(feature = clocks-timezone)
     use system-clock.{instant};
 
-    /// Return information needed to display the given `instant`. This includes
-    /// the UTC offset, the time zone name, and a flag indicating whether
-    /// daylight saving time is active.
+    /// Return information needed to display the given `instant` in the
+    /// currently configured time zone. This includes the UTC offset, the time
+    /// zone name, and a flag indicating whether daylight saving time is active.
     ///
-    /// If the timezone cannot be determined for the given `instant`, return a
+    /// If the currently configured timezone cannot be determined, return a
     /// `timezone-display` for `UTC` with a `utc-offset` of 0 and no daylight
     /// saving time.
     @unstable(feature = clocks-timezone)
@@ -19,7 +19,8 @@ interface timezone {
     @unstable(feature = clocks-timezone)
     utc-offset: func(when: instant) -> s32;
 
-    /// Information useful for displaying the timezone of a specific `instant`.
+    /// Information useful for displaying a specific `instant` in the currently
+    /// configured time zone.
     ///
     /// This information may vary within a single `timezone` to reflect daylight
     /// saving time adjustments.