Update changelog for v4.0.0

Author: Krusen

CHANGELOG.md

@@ -6,14 +6,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+...
+
+## [4.0.0] - 2021-01-23
 ### Changed
-- Changed target frameworks to:
+- Changed supported frameworks to:
   - .NET Standard 2.0
   - .NET Standard 2.1
   - .NET Core App 2.1
   - .NET 5.0
-
-...
+- `Torrent.Pieces` can now only be set to an array with a length which is a multiple of 20.
 
 ## [3.1.4] - 2020-03-06
 ### Fixed
@@ -157,8 +159,9 @@ and generally better usability; albeit a bit more complex.
 ## [1.0.0] - 2015-09-19
 
 
-[Unreleased]: ../../compare/v3.1.4...HEAD
-[3.1.4]: ../../compare/v3.1.4...v3.1.4
+[Unreleased]: ../../compare/v4.0.0...HEAD
+[4.0.0]: ../../compare/v3.1.4...v4.0.0
+[3.1.4]: ../../compare/v3.1.3...v3.1.4
 [3.1.3]: ../../compare/v3.1.0...v3.1.3
 [3.1.0]: ../../compare/v3.0.1...v3.1.0
 [3.0.1]: ../../compare/v3.0.0...v3.0.1