Clarify that core::range::RangeInclusive does not have special syntax

I'm ignoring the fact that there's a feature to change the behavior of
the syntax. I just want to help prevent confusing the people reading
the docs.

(cherry picked from commit 092f0ca1bd)

library/core/src/range.rs

@@ -228,21 +228,24 @@ fn from(value: legacy::Range<T>) -> Self {
     }
 }
 
-/// A range bounded inclusively below and above (`start..=last`).
+/// A range bounded inclusively below and above.
 ///
-/// The `RangeInclusive` `start..=last` contains all values with `x >= start`
+/// The `RangeInclusive` contains all values with `x >= start`
 /// and `x <= last`. It is empty unless `start <= last`.
 ///
 /// # Examples
 ///
-/// The `start..=last` syntax is a `RangeInclusive`:
-///
 /// ```
 /// use core::range::RangeInclusive;
 ///
 /// assert_eq!(RangeInclusive::from(3..=5), RangeInclusive { start: 3, last: 5 });
 /// assert_eq!(3 + 4 + 5, RangeInclusive::from(3..=5).into_iter().sum());
 /// ```
+///
+/// # Edition notes
+///
+/// It is planned that the syntax  `start..=last` will construct this
+/// type in a future edition, but it does not do so today.
 #[lang = "RangeInclusiveCopy"]
 #[derive(Clone, Copy, PartialEq, Eq, Hash)]
 #[stable(feature = "new_range_inclusive_api", since = "1.95.0")]