Add link to changelog of new major version

CHANGELOG.md

@@ -2,10 +2,11 @@
 
 ## Current version
 
-* [Spyder 5 changes](./changelogs/Spyder-5.md)
+* [Spyder 6 changes](./changelogs/Spyder-6.md)
 
 ## Older versions
 
+* [Spyder 5 changes](./changelogs/Spyder-5.md)
 * [Spyder 4 changes](./changelogs/Spyder-4.md)
 * [Spyder 3 changes](./changelogs/Spyder-3.md)
 * [Spyder 2 changes](./changelogs/Spyder-2.md)