Rollup merge of #46986 - nvzqz:basic-usage, r=steveklabnik

Add "Basic Usage" to int min_value and max_value docs

This adds "Basic Usage:" to the docs of `min_value` and `max_value`, which makes it consistent with docs of other integer methods.

src/libcore/num/mod.rs

@@ -103,6 +103,8 @@ macro_rules! int_impl {
         ///
         /// # Examples
         ///
+        /// Basic usage:
+        ///
         /// ```
         /// assert_eq!(i8::min_value(), -128);
         /// ```
@@ -116,6 +118,8 @@ macro_rules! int_impl {
         ///
         /// # Examples
         ///
+        /// Basic usage:
+        ///
         /// ```
         /// assert_eq!(i8::max_value(), 127);
         /// ```
@@ -1252,6 +1256,8 @@ macro_rules! uint_impl {
         ///
         /// # Examples
         ///
+        /// Basic usage:
+        ///
         /// ```
         /// assert_eq!(u8::min_value(), 0);
         /// ```
@@ -1263,6 +1269,8 @@ macro_rules! uint_impl {
         ///
         /// # Examples
         ///
+        /// Basic usage:
+        ///
         /// ```
         /// assert_eq!(u8::max_value(), 255);
         /// ```