Rollup merge of rust-lang#70782 - faern:use-assoc-float-consts, r=dtolnay

Stop importing the float modules in documentation

Follow up to rust-lang#69860. I realized I had not searched for and fixed this for the float values. So with this PR they also use the associated constants instead of the module level constants.

For the documentation where it also was using the `consts` submodule I opted to change it to import that directly. This becomes more in line with how other docs that use the `consts` submodule looks. And it also makes it so there are not two `f32` or `f64` things in the current namespace (both the module and the primitive type) and then hopefully confusing documentation readers less.

r? @dtolnay

Author: Centril

Diff for: src/libcore/num/f32.rs

@@ -394,9 +394,7 @@ impl f32 {
     /// Converts radians to degrees.
     ///
     /// ```
-    /// use std::f32::consts;
-    ///
-    /// let angle = consts::PI;
+    /// let angle = std::f32::consts::PI;
     ///
     /// let abs_difference = (angle.to_degrees() - 180.0).abs();
     ///
@@ -413,11 +411,9 @@ impl f32 {
     /// Converts degrees to radians.
     ///
     /// ```
-    /// use std::f32::consts;
-    ///
     /// let angle = 180.0f32;
     ///
-    /// let abs_difference = (angle.to_radians() - consts::PI).abs();
+    /// let abs_difference = (angle.to_radians() - std::f32::consts::PI).abs();
     ///
     /// assert!(abs_difference <= f32::EPSILON);
     /// ```

Diff for: src/libcore/num/f64.rs

@@ -407,9 +407,7 @@ impl f64 {
     /// Converts radians to degrees.
     ///
     /// ```
-    /// use std::f64::consts;
-    ///
-    /// let angle = consts::PI;
+    /// let angle = std::f64::consts::PI;
     ///
     /// let abs_difference = (angle.to_degrees() - 180.0).abs();
     ///
@@ -427,11 +425,9 @@ impl f64 {
     /// Converts degrees to radians.
     ///
     /// ```
-    /// use std::f64::consts;
-    ///
     /// let angle = 180.0_f64;
     ///
-    /// let abs_difference = (angle.to_radians() - consts::PI).abs();
+    /// let abs_difference = (angle.to_radians() - std::f64::consts::PI).abs();
     ///
     /// assert!(abs_difference < 1e-10);
     /// ```

Diff for: src/libcore/ops/range.rs

@@ -98,8 +98,6 @@ impl<Idx: PartialOrd<Idx>> Range<Idx> {
     /// # Examples
     ///
     /// ```
-    /// use std::f32;
-    ///
     /// assert!(!(3..5).contains(&2));
     /// assert!( (3..5).contains(&3));
     /// assert!( (3..5).contains(&4));
@@ -198,8 +196,6 @@ impl<Idx: PartialOrd<Idx>> RangeFrom<Idx> {
     /// # Examples
     ///
     /// ```
-    /// use std::f32;
-    ///
     /// assert!(!(3..).contains(&2));
     /// assert!( (3..).contains(&3));
     /// assert!( (3..).contains(&1_000_000_000));
@@ -282,8 +278,6 @@ impl<Idx: PartialOrd<Idx>> RangeTo<Idx> {
     /// # Examples
     ///
     /// ```
-    /// use std::f32;
-    ///
     /// assert!( (..5).contains(&-1_000_000_000));
     /// assert!( (..5).contains(&4));
     /// assert!(!(..5).contains(&5));
@@ -453,8 +447,6 @@ impl<Idx: PartialOrd<Idx>> RangeInclusive<Idx> {
     /// # Examples
     ///
     /// ```
-    /// use std::f32;
-    ///
     /// assert!(!(3..=5).contains(&2));
     /// assert!( (3..=5).contains(&3));
     /// assert!( (3..=5).contains(&4));
@@ -581,8 +573,6 @@ impl<Idx: PartialOrd<Idx>> RangeToInclusive<Idx> {
     /// # Examples
     ///
     /// ```
-    /// use std::f32;
-    ///
     /// assert!( (..=5).contains(&-1_000_000_000));
     /// assert!( (..=5).contains(&5));
     /// assert!(!(..=5).contains(&6));
@@ -721,8 +711,6 @@ pub trait RangeBounds<T: ?Sized> {
     /// # Examples
     ///
     /// ```
-    /// use std::f32;
-    ///
     /// assert!( (3..5).contains(&4));
     /// assert!(!(3..5).contains(&2));
     ///