Move std::char8_t to library section.

CPP20.md

@@ -13,7 +13,6 @@ C++20 includes the following new language features:
 - [class types in non-type template parameters](#class-types-in-non-type-template-parameters)
 - [constexpr virtual functions](#constexpr-virtual-functions)
 - [explicit(bool)](#explicitbool)
-- [char8_t](#char8_t)
 - [immediate functions](#immediate-functions)
 - [using enum](#using-enum)
 
@@ -30,6 +29,7 @@ C++20 includes the following new library features:
 - [std::bit_cast](#stdbit_cast)
 - [std::midpoint](#stdmidpoint)
 - [std::to_array](#stdto_array)
+- [char8_t](#char8_t)
 
 ## C++20 Language Features
 
@@ -298,12 +298,6 @@ foo b = "123"; // ERROR: explicit constructor is not a candidate (explicit speci
 foo c {"123"}; // OK
 ```
 
-### char8_t
-Provides a standard type for representing UTF-8 strings.
-```c++
-char8_t utf8_str[] = u8"\u0123";
-```
-
 ### Immediate functions
 Similar to `constexpr` functions, but functions with a `consteval` specifier must produce a constant. These are called `immediate functions`.
 ```c++
@@ -493,6 +487,12 @@ int a[] = {1, 2, 3};
 std::to_array(a); // returns `std::array<int, 3>`
 ```
 
+### char8_t
+Provides a standard type for representing UTF-8 strings.
+```c++
+char8_t utf8_str[] = u8"\u0123";
+```
+
 ## Acknowledgements
 * [cppreference](http://en.cppreference.com/w/cpp) - especially useful for finding examples and documentation of new library features.
 * [C++ Rvalue References Explained](http://thbecker.net/articles/rvalue_references/section_01.html) - a great introduction I used to understand rvalue references, perfect forwarding, and move semantics.