Google Apps Script allows you to easily create dialogs with HTML (.html). However, some things like READMEs and CHANGELOGs are easier and more likely to be maintained as Markdown (.md) files.

I'm imagining a workflow where I could write some Typescript like:

function showChangelog() {
    var html = HtmlService.createHtmlOutputFromFile('CHANGELOG')
        .setWidth(480)

On https://saxob.ga/ when you click you result I have made it go to the link in a new tab.

There are other ways to do it instead of opening the link, for exmaple you could make it click to copy.