revert: undo accidental changes to round docs

Author: ruancomelli

library/std/src/f64.rs

@@ -72,8 +72,13 @@ impl f64 {
     pub const fn ceil(self) -> f64 {
         core::f64::math::ceil(self)
     }
+
+    /// Returns the nearest integer to `self`. If a value is half-way between two
+    /// integers, round away from `0.0`.
+    ///
     /// This function always returns the precise result.
     ///
+    /// # Examples
     ///
     /// ```
     /// let f = 3.3_f64;