Project Template config json file

After following a tutorial for creating a Project Template in:
https://developer.atlassian.com/server/jira/platform/creating-a-project-template/

I can see that there is a json-config file: src/main/config/config.json.
As shown in the json config file below there is an easy way to create a new issue type, and workflow.

What else does this json config file is capable of, can we create a custom field, a screen, and where can I find the documentation?

{
    "issue-type-scheme":
    {
        "name": "my.project.template.issuetype.scheme.name",
        "description": "my.project.template.issuetype.scheme.description",
        "issue-types": [
            {
                "key": "issueType1",
                "name": "New Feature",
                "description": "A new feature of the product, which has yet to be developed.",
                "icon": "/images/icons/newfeature.png",
                "workflow": "wf1"
            },
            {
                "key": "issueType2",
                "name": "Bug",
                "description": "A problem which impairs or prevents the functions of the product.",
                "icon": "/images/icons/bug.png"
            },
            {
                "key": "issueType3",
                "name": "Sub-Task",
                "description": "The sub-task of the issue",
                "icon": "/images/icons/subtask_alternate.png",
                "sub-task": true,
                "workflow": "wf2"
            }
        ]
    },
    "workflow-scheme":
    {
        "name": "my.project.template.workflow.scheme.name",
        "description": "my.project.template.workflow.scheme.description",
        "default-workflow": "wf1",
        "workflows": [
            {
                "key": "wf1",
                "name": "my.project.template.workflow.wf1.name",
                "workflow-bundle": "/wfb/Issue-Tracking-Workflow.jwb"
            },
            {
                "key": "wf2",
                "name": "my.project.template.workflow.wf2.name",
                "workflow-bundle": "/wfb/Software-Development-Workflow.jwb"
            }
        ]
    }
}