update changelog & issues

CHANGELOG.md

@@ -8,7 +8,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 
 ### v3.9.x - [Unreleased]
 
-### v3.9.8.4 - 2019-08-27
+### v3.9.8.4 - 2019-08-28
 
 #### Added
 
@@ -19,17 +19,16 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Domain/Subdomain detection based on public domain suffixes list
 - Increase Nginx & MariaDB systemd open_files limits
 - Cronjob to update Cloudflare IPs list
-- mariadb-backup to perform full and non-blocking databases backup
+- mariadb-backup to perform full and non-blocking databases backup (only installation)
 - Nginx configuration check before performing start/reload/restart
 - Nginx mapping to proxy web-socket connections
-- Nginx configuration rollback in case of failure with `wo stack upgrade --nginx`
 
 #### Changed
 
 - eXplorer filemanager isn't installed with WordOps dashboard anymore, and a flag `--extplorer` is available. But it's still installed when running the command `wo stack install`
 - Template rendering function now check for a .custom file before overwriting a configuration by default.
 - flag `--letsencrypt=subdomain` is not required anymore, you can use `--letsencrypt` or `-le`
-- Simplify APT GPG Keys import
+- Simplifiy and decrease duration of `apt-key` GPG keys import
 
 #### Fixed