Updated create a block grid programatically section of "Block Grid" page

[AndyButland]

📋 Description

This PR updates the code sample and instructions for the "Creating a Block Grid programmatically" on the "Block Grid" page

📎 Related Issues (if applicable)

#7599

✅ Contributor Checklist

I've followed the Umbraco Documentation Style Guide and can confirm that:

• Code blocks are correctly formatted.
• Sentences are short and clear (preferably under 25 words).
• Passive voice and first-person language (“we”, “I”) are avoided.
• Relevant pages are linked.
• All links work and point to the correct resources.
• Screenshots or diagrams are included if useful.
• Any code examples or instructions have been tested.
• Typos, broken links, and broken images are fixed.

Product & Version (if relevant)

CMS 16 and 17

Deadline (if relevant)

Can be reviewed and published at any time.

[eshanrnh]

@AndyButland is this ready for internal or docs review? Asking cz the task is in internal community review status 😊

[AndyButland]

You can review this one please @eshanrnh. It's an update to part of a page that HQ were asked to look into, where there rest of the page is being handled by a community team member. So it won't close the linked issue, rather is just related to it.

[eshanrnh]

Thanks for the PR, @AndyButland 🙌 The PR looks good.

I have added suggestions to start the steps/list with an action word and cleaned up the long, messy image URLs. I'll take care of those.

[github-actions]

The Link Checker found broken links in your PR.
Please review the following list:

Broken links found in: 16/umbraco-cms/fundamentals/setup/upgrading/version-specific/README.md

⚠ Unknown error → [500] https://our.umbraco.com/download/releases/1300 |#124; Rejected status code (this depends on your "accept" configuration): Internal Server Error