Update changelog for v6.0.0

Author: JonasAlfredsson

docs/changelog.md

@@ -1,5 +1,11 @@
 # Changelog
 
+### 6.0.0
+- Certbot updated two major versions (`2.11.0` -> `4.1.1`).
+  - This is the main reason for making a major version bump for us.
+- The scripts now handle nested folders in `user_conf.d/`.
+- It is now possible to have [multiple credentials](./certbot_authenticators.md#unique-credentials-files) files for the same DNS authenticator.
+
 ### 5.6.0
 - Added gandi DNS authenticator.
   - PR by [@benedicteb][58]

docs/dockerhub_tags.md

@@ -17,6 +17,7 @@ are updated.
 
 | Major | Minor | Patch | Nginx              |
 | ----: | ----: | ----: | :----------------- |
+| 6     | 6.0   | 6.0.0 | 6.0.0-nginx1.28.0  |
 | 5     | 5.6   | 5.6.0 | 5.6.0-nginx1.28.0  |
 |       |       |       | 5.6.0-nginx1.27.5  |
 |       | 5.5   | 5.5.0 | 5.5.0-nginx1.27.5  |