Remove link to release from changelog release entry template

In other projects, we found this to be more cumbersome to maintain than
the use it delivered by making the header clickable.

Author: mokagio

CHANGELOG.md

@@ -7,7 +7,7 @@ The format of this document is inspired by [Keep a Changelog](https://keepachang
 When releasing a new version:
 
 1. Remove any empty section (those with `_None._`)
-2. Update the `## Unreleased` header to `## [<version_number>](https://github.com/wordpress-mobile/WordPressUI-iOS/releases/tag/<version_number>)`
+2. Update the `## Unreleased` header to `## <version_number>`
 3. Add a new "Unreleased" section for the next iteration, by copy/pasting the following template:
 
 ## Unreleased