Code for general and documentation properties in property panel

Hi,
where can i find the code for general and documentation properties in the property panel.
I would like to extend the panel with custom properties, I am trying to create a group similar to general.
I have been refering this https://github.com/bpmn-io/bpmn-js-examples/tree/main/properties-panel-extension.

please help.

The link you mentioned is the right place to look. Is there anything in particular that you need help with?

I would like to add multiple text fields in one group, whats the best way to go about doing that.

While defining the group, you can add multiple entries:

magicGroup = {
    id: 'magic',
    label: translate('Magic properties'),
    entries: [
      ...spellProps(element),
      ...moreProps(element)
    ];
 };