Fix data-diff first line bug

[fry69]

Fix #56

• diff symbol renders now inside the code block for the first line
• added example for diff on the first line
• tests desperately needed

I am happy with this so far, awaiting comments.

[netlify[bot]]

✅ Deploy Preview for ember-showdown-prism ready!

Name	Link
🔨 Latest commit	ea187dd57c5dc8d21342b08d87b2b68293c53ed4
🔍 Latest deploy log	https://app.netlify.com/sites/ember-showdown-prism/deploys/64e4c4a2f43c650008b2584d
😎 Deploy Preview	https://deploy-preview-57--ember-showdown-prism.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[fry69]

No clue how to fix this, I did not touch anything knowingly that could provoke an Ember is not defined error. Please enlighten me.

Built project successfully. Stored in "/tmp/tests-dist-2023722-1936-1ggxhms.oalu".
not ok 1 Chrome 115.0 - [undefined ms] - Global error: Uncaught ReferenceError: Ember is not defined at http://localhost:7357/assets/vendor.js, line 3860
    ---
        browser log: |
            {"type":"error","text":"Uncaught ReferenceError: Ember is not defined at http://localhost:7357/assets/vendor.js, line 3860\n","testContext":{}}

[mansona]

@fry69 regarding the Embroider error, you can ignore it. It's because of a new embroider feature that was recently added in https://github.com/embroider-build/embroider/pull/1521

I will fix that at a later date, and it's nothing that you have done to cause that issue