Added readme.

README.md

@@ -0,0 +1,65 @@
+# Hurricane Electric dynamic DNS updater
+
+This is a small Bash utility script that can be used to update your dynamic DNS entries if you use the [Free DNS service from Hurricane Electric](https://dns.he.net/).
+
+It tries to remain minimal in terms of prerequisites to make it usable on various modern Linux distributions.
+
+## Quick start guide
+
+_Step 1._ Clone this repository:
+
+    git clone [email protected]:peterbudai/he-dns-update.git
+
+_Step 2._ Edit the provided example configuration file ([`dns-update.conf`](dns-update.conf)) and fill it with your hostnames and dynamic DNS entry keys.
+
+_Step 3._ Run the utility:
+
+    ./dns-update.sh
+
+## Configuration
+
+The configuration file should always be placed next to the script. It should bear the same file name, except the `.conf` extension. It has a very straightforward simple tabular format:
+
+* Everything starting with a pound sign (`#`) is considered as comment and discarded.
+* Each line describes a single dynamic DNS entry that you set up at HE.
+* Each entry consists of 3 columns, separated with any number and kind of whitespace:
+    1. IP protocol version: `4` (for A records) or `6` (for AAAA records). 
+    2. The fully qualified hostname of the entry, eg. `test.example.org`
+    3. The key for the dynamic DNS entry. I suggest generating one using the HE web form, it is usually a sequence of 16 alphanumeric characters, eg. `AbCd1234EfGh5678`.
+
+## Running
+
+### Manually
+
+You can always run the script manually, which will immediately try to update all DNS records specified in the config file.
+
+    ./dns-update.sh
+
+You can use this option to test your configuration. To get more feedback in case of an error, specify the `-v` or `--verbose` flag when running:
+
+    ./dns-update.sh -v
+
+### Automatically
+
+I suggest adding this script to your `crontab`. This way it will be run at regular intervals and will always keep your IP address up to date.
+
+An example cron configuration that runs the update every 15 minutes would look like the following (in this case the script and the config file is copied to the `/etc/cron.d` directory):
+
+    */15 * * * *    root    /etc/cron.d/dns-update
+
+Alternatively, you can set up any kind of network interface hooks that will trigger running the DNS update. This is more advanced and depends heavily on the Linus distribution you use.
+
+License
+-------
+
+This utility is distributed under the [MIT License](LICENSE.md).
+
+Contributing
+------------
+
+Feel free to file an [issue](https://github.com/peterbudai/he-dns-update/issues) or open a [pull request](https://github.com/peterbudai/he-dns-update/pulls).
+
+Acknowledgement
+---------------
+
+Inspired by [this Gist](https://gist.github.com/joemiller/9fcbf1c953a8ed1095e95fe4396cec4a) from [joe miller](https://github.com/joemiller).