add section about container timezones to the README

README.md

@@ -17,6 +17,7 @@ It handles __recurring or one-off backups of Docker volumes__ to a __local direc
   - [Send email notifications on failed backup runs](#send-email-notifications-on-failed-backup-runs)
   - [Encrypting your backup using GPG](#encrypting-your-backup-using-gpg)
   - [Restoring a volume from a backup](#restoring-a-volume-from-a-backup)
+  - [Setting the timezone the container runs in](#setting-the-timezone-the-container-runs-in)
   - [Using with Docker Swarm](#using-with-docker-swarm)
   - [Manually triggering a backup](#manually-triggering-a-backup)
 - [Recipes](#recipes)
@@ -358,6 +359,27 @@ In case you need to restore a volume from a backup, the most straight forward pr
 
 Depending on your setup and the application(s) you are running, this might involve other steps to be taken still.
 
+### Setting the timezone the container runs in
+
+By default a container based on this image will run in the UTC timezone.
+As the image is designed to be as small as possible, additional timezone data is not included.
+In case you want to run your cron rules in your local timezone (respecting DST and similar), you can mount your Docker host's `/etc/timezone` and `/etc/localtime` in read-only mode:
+
+```
+version: '3'
+
+services:
+  backup:
+    image: offen/docker-volume-backup:latest
+    volumes:
+      - data:/backup/my-app-backup:ro
+      - /etc/timezone:/etc/timezone:ro
+      - /etc/localtime:/etc/localtime:ro
+
+volumes:
+  data:
+```
+
 ### Using with Docker Swarm
 
 By default, Docker Swarm will restart stopped containers automatically, even when manually stopped.
@@ -593,3 +615,5 @@ Local copies of backups can also be pruned once they reach a certain age.
 - InfluxDB specific functionality from the original image was removed.
 - `arm64` and `arm/v7` architectures are supported.
 - Docker in Swarm mode is supported.
+- Notifications on failed backups are supported
+- IAM authentication through instance profiles is supported