Rollup merge of rust-lang#55251 - NieDzejkob:master, r=TimNN

Fix a typo in the documentation of RangeInclusive

src/libcore/ops/range.rs

@@ -304,7 +304,7 @@ impl<Idx: PartialOrd<Idx>> RangeTo<Idx> {
     }
 }
 
-/// An range bounded inclusively below and above (`start..=end`).
+/// A range bounded inclusively below and above (`start..=end`).
 ///
 /// The `RangeInclusive` `start..=end` contains all values with `x >= start`
 /// and `x <= end`.  It is empty unless `start <= end`.