Extend readme and add some hints in config

Signed-off-by: Eduard Veit <developer@ev21.de>

README.md

@@ -1,27 +1,52 @@
 # Nameserver update for INWX (nsupdate)
 
-This shell script implements [dynamic DNS](https://en.wikipedia.org/wiki/Dynamic_DNS) using the [inwx](https://www.inwx.de/) API, i.e., it updates nameserver entries with your current WAN IPv4 and IPv6 addresses.
+This shell script implements [dynamic DNS](https://en.wikipedia.org/wiki/Dynamic_DNS) using the [DomRobot XML-RPC API](https://www.inwx.de/de/help/apidoc/f/ch02s13.html#nameserver.updateRecord) by [INWX](https://www.inwx.de/).  
+This script can update nameserver entries with your current WAN IPv4 and IPv6 addresses.  
+It uses the `nameserver.updateRecord` method of the API.  
+
+advantage: You don't need payed dynDNS-accounts for multiple domains.  
+disadvantage: The minimum TTL is 300 (5 minutes). The dynDNS-Service allowes 60 (1 minute).
+
+There exists the `dyndns.updateRecord` method in the DomRobot API. Therefore you need a DynDNS-account by INWX. If you need this option, feel free to change the script to your needs.  
 
 ## Requirements
 
-In order to run you need to have _curl_ and _awk_ installed, as well as _drill_ or _nslookup_.
+In order to run the script you need to have installed the following command line tools:
+
+- _curl_
+- _awk_
+- _nslookup_ or _drill_
 
 ## Installation
 
-Simply download the `master.zip` and extract it, e.g., using `wget` and `7z x master.zip`.
+Simply clone this project or download the `master.zip` and extract it, e.g., using `wget` and `7z x master.zip`.
 
 Place your config files in the `nsupdate.d` folder. A `dist.config.sample` is provided. At least one config file needs to exist, ending with `.config.  
-All .config files will be processed by looping them.  
+All .config files (one for each dns-record) will be processed by looping them.  
 Simply copy the provided dist.config.sample and adjust your config to your needs.
 For home.example.com you may create:  
 home.example.com-ipv4.config and/or  
 home.example.com-ipv6.config  
 
+
+## Run nsupdate by cron
+With `crontab -e` you can add the following line for running the script every 5 minutes:  
+`*/5 * * * * bash /home/$USER/nsupdate/nsupdate.sh`  
+
 ## Changelog
 
+**2020-05-11**
+
+- Updated Readme with some hints
+- Updated config.sample with a hint for TTL
+
+**2020-03-31**
+
+- Made time to live configurable
+
 **2019-12-20**
 
-- Fixing API-XML syntax
+- Fixed DomRobot XML-RPC API syntax
 - Added some more documentation
 
 **2015-07-22**

nsupdate.d/dist.config.sample

@@ -19,10 +19,12 @@ IPV6="NO"
 # Update an MX record.
 MX="NO"
 
-# Suppress all messages.
+# Suppress all messages and deactivates logging.
 SILENT="NO"
 
-# Time to Live
+# TTL: Time to Live
+# default TTL setting by inwx is 3600 (1 hour)
+# minimum TTL allowed by inwx is 300 (5 minutes) for regular nameserver record updates
 TTL=300
 
 # Login credentials for the inwx admin interface