Add disclaimer to short generic location format (#6095)

components/datetime/src/fieldsets.rs

@@ -345,6 +345,10 @@ macro_rules! impl_zone_combo_helpers {
             }
             /// Associates this field set with a short generic non-location format time zone, as in
             /// “PT”.
+            ///
+            /// Note: short time zones names are usually only available for time zones in the country
+            /// associated with a locale (so "PT" is in `en`, but not in `en-GB`). Most time zones will
+            /// fall back to the significantly longer location format (e.g. "Los Angeles Time" for `en-GB`).
             #[inline]
             pub fn with_zone_generic(self) -> Combo<Self, Vs> {
                 Combo::new(self, Vs::new())
@@ -1512,6 +1516,10 @@ impl_zone_marker!(
 );
 
 impl_zone_marker!(
+    /// Note: short time zones names are usually only available for time zones in the country
+    /// associated with a locale (so "PT" is in `en`, but not in `en-GB`). Most time zones will
+    /// fall back to the significantly longer location format (e.g. "Los Angeles Time" in `en-GB`).
+    ///
     /// Since non-location names might change over time,
     /// this time zone style requires a reference time.
     ///