This PR will add support for crontab scheduler instead of default on which is based on minutes.

I’m not Go developer so I don’t know if this is by standard but it works in my local build :)

I don’t know if async functions are handled properly, for example, so I think you should definitely review everything.

Will it be possible to add additional information to log which operations are performed, similar to https://github.com/zjstraus/name-dyndns

For example:

dynamic-dns-update_1  | 2021/12/21 12:43:21 Detected configuration for [DOMAIN]
dynamic-dns-update_1  | 2021/12/21 12:43:23 Checking against [HOST+DOMAIN].
dynamic-dns-update_1  | 2021/12/21 12:43:23 Running update check for [HOST].
dynamic-dns-update_1  | 2021/12/21 12:43:23 Update complete.
dynamic-dns-update_1  | 2021/12/21 12:43:23 Will update again in 10800 seconds.

Improve checks on PRs (vet & go-lint & docker is able to build the image)

Also automate the build so publishes by itself once a PR is merged

Fix linting messages

Based on the request at #3.

Add support for cron format. This stills allows simple configs using "@every 1h" format.

Also this provides support to define multiple A registers at once from the same machine.

Validate the config so we are sure all properties are correct before starting

Finally provide a makefile for easier deveolpment

This Pr has been tagged as v0.1.0 on docker hub and also updated latest with it. I had also pushed a v0.0.0 with the previous version