Added Readme

Readme.md

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+# Dnscontrol-Sync
+
+This images is designed to synchronise changes between Nameserver-Providers (like PowerDNS or Cloudflare-DNS).
+
+It uses [dnscontrol](https://github.com/StackExchange/dnscontrol) to pull & push these changes
+and DNS-NOTIFY for event-driven updates.
+
+---
+
+## Current state
+
+At the moment, this program can only pull changes from PowerDns and will push it to any other provider specified for that domain in `dnsconfig.js` (from dnscontrol).
+
+Furthermore there is an option to auto-rename a zone (e.g. public-zone has suffix .public), because e.g. PowerDns does not support "views".
+
+It is very likely the software will make mistakes when multiple change-events were executed when the first one was not finished yet.
+It's planned to have a queue for that.
+
+---
+
+## How it works
+
+PowerDns has this program as "slave" and will send a DNS-NOTIFY when zone-information has changed.
+We will then use dnscontrol to pull the whole zone into a dnscontrol-formatted JavaScript-file,
+modify it to match our needs and push it using the configured dnscontrol config.
+
+### In Short
+
+1. DNS-NOTIFY by PowerDns
+2. dnscontrol get-zones PowerDns
+3. Modify generated file
+4. dnscontrol push
+
+---
+
+## Which Providers are supported
+
+Check out the dnscontrol-documentation for further information about providers, setup and compatability of special records and settings:
+
+https://stackexchange.github.io/dnscontrol/provider-list