The provided repository code allows you to redirect requests from GitHub to Discord using webhooks, so you can customise your messages and use them to your advantage. It is also worth noting that at the moment only push and merge events are supported, but you can add other events yourself to process them further by analysing the common template.
First you need to set up the configuration in the config.php file, at this point you only need two keys: secret and webhook fields.
The second step is to install these PHP scripts on your server for further processing, then bind the webhook in GitHub and configure it yourself.
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About webhooks (GitHub)
About webhooks (Discord)