CHANGELOG: Move reference links to each section

The list of reference links at the bottom gets pretty ungainly. Move
references to the section for each version.

This should have no effect on the actual Markdown output.

CHANGELOG.md

@@ -14,6 +14,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Add `atomic.Uintptr` type for atomic operations on `uintptr` values.
 - Add `atomic.UnsafePointer` type for atomic operations on `unsafe.Pointer` values.
 
+[1.8.0]: https://github.com/uber-go/atomic/compare/v1.7.0...v1.8.0
+
 ## [1.7.0] - 2020-09-14
 ### Added
 - Support JSON serialization and deserialization of primitive atomic types.
@@ -25,63 +27,72 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Removed
 - Remove dependency on `golang.org/x/{lint, tools}`.
 
+[1.7.0]: https://github.com/uber-go/atomic/compare/v1.6.0...v1.7.0
+
 ## [1.6.0] - 2020-02-24
 ### Changed
 - Drop library dependency on `golang.org/x/{lint, tools}`.
 
+[1.6.0]: https://github.com/uber-go/atomic/compare/v1.5.1...v1.6.0
+
 ## [1.5.1] - 2019-11-19
 - Fix bug where `Bool.CAS` and `Bool.Toggle` do work correctly together
   causing `CAS` to fail even though the old value matches.
 
+[1.5.1]: https://github.com/uber-go/atomic/compare/v1.5.0...v1.5.1
+
 ## [1.5.0] - 2019-10-29
 ### Changed
 - With Go modules, only the `go.uber.org/atomic` import path is supported now.
   If you need to use the old import path, please add a `replace` directive to
   your `go.mod`.
 
+[1.5.0]: https://github.com/uber-go/atomic/compare/v1.4.0...v1.5.0
+
 ## [1.4.0] - 2019-05-01
 ### Added
  - Add `atomic.Error` type for atomic operations on `error` values.
 
+[1.4.0]: https://github.com/uber-go/atomic/compare/v1.3.2...v1.4.0
+
 ## [1.3.2] - 2018-05-02
 ### Added
 - Add `atomic.Duration` type for atomic operations on `time.Duration` values.
 
+[1.3.2]: https://github.com/uber-go/atomic/compare/v1.3.1...v1.3.2
+
 ## [1.3.1] - 2017-11-14
 ### Fixed
 - Revert optimization for `atomic.String.Store("")` which caused data races.
 
+[1.3.1]: https://github.com/uber-go/atomic/compare/v1.3.0...v1.3.1
+
 ## [1.3.0] - 2017-11-13
 ### Added
 - Add `atomic.Bool.CAS` for compare-and-swap semantics on bools.
 
 ### Changed
 - Optimize `atomic.String.Store("")` by avoiding an allocation.
 
+[1.3.0]: https://github.com/uber-go/atomic/compare/v1.2.0...v1.3.0
+
 ## [1.2.0] - 2017-04-12
 ### Added
 - Shadow `atomic.Value` from `sync/atomic`.
 
+[1.2.0]: https://github.com/uber-go/atomic/compare/v1.1.0...v1.2.0
+
 ## [1.1.0] - 2017-03-10
 ### Added
 - Add atomic `Float64` type.
 
 ### Changed
 - Support new `go.uber.org/atomic` import path.
 
+[1.1.0]: https://github.com/uber-go/atomic/compare/v1.0.0...v1.1.0
+
 ## [1.0.0] - 2016-07-18
 
 - Initial release.
 
-[1.8.0]: https://github.com/uber-go/atomic/compare/v1.7.0...v1.8.0
-[1.7.0]: https://github.com/uber-go/atomic/compare/v1.6.0...v1.7.0
-[1.6.0]: https://github.com/uber-go/atomic/compare/v1.5.1...v1.6.0
-[1.5.1]: https://github.com/uber-go/atomic/compare/v1.5.0...v1.5.1
-[1.5.0]: https://github.com/uber-go/atomic/compare/v1.4.0...v1.5.0
-[1.4.0]: https://github.com/uber-go/atomic/compare/v1.3.2...v1.4.0
-[1.3.2]: https://github.com/uber-go/atomic/compare/v1.3.1...v1.3.2
-[1.3.1]: https://github.com/uber-go/atomic/compare/v1.3.0...v1.3.1
-[1.3.0]: https://github.com/uber-go/atomic/compare/v1.2.0...v1.3.0
-[1.2.0]: https://github.com/uber-go/atomic/compare/v1.1.0...v1.2.0
-[1.1.0]: https://github.com/uber-go/atomic/compare/v1.0.0...v1.1.0
 [1.0.0]: https://github.com/uber-go/atomic/releases/tag/v1.0.0