consistent docs for f*.rs functions

Author: LorrensP-2158466

library/std/src/num/f128.rs

@@ -467,10 +467,10 @@ impl f128 {
     /// # #[cfg(not(miri))]
     /// # #[cfg(target_has_reliable_f128_math)] {
     ///
-    /// let f = std::f128::consts::FRAC_PI_2;
+    /// let f = std::f128::consts::FRAC_PI_4;
     ///
     /// // asin(sin(pi/2))
-    /// let abs_difference = (f.sin().asin() - std::f128::consts::FRAC_PI_2).abs();
+    /// let abs_difference = (f.sin().asin() - f).abs();
     ///
     /// assert!(abs_difference <= f128::EPSILON);
     /// # }

library/std/src/num/f16.rs

@@ -432,10 +432,10 @@ impl f16 {
     /// # #[cfg(not(miri))]
     /// # #[cfg(target_has_reliable_f16_math)] {
     ///
-    /// let f = std::f16::consts::FRAC_PI_2;
+    /// let f = std::f16::consts::FRAC_PI_4;
     ///
     /// // asin(sin(pi/2))
-    /// let abs_difference = (f.sin().asin() - std::f16::consts::FRAC_PI_2).abs();
+    /// let abs_difference = (f.sin().asin() - f).abs();
     ///
     /// assert!(abs_difference <= f16::EPSILON);
     /// # }