docs(blog): update em vs rem article for clarity and snippets

[necatiozmen]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://refine.dev/docs/guides-concepts/contributing/#commit-convention

Bugs / Features

• Related issue(s) linked
• Tests for the changes have been added
• Docs have been added / updated
• Changesets have been added https://refine.dev/docs/guides-concepts/contributing/#creating-a-changeset

What is the current behavior?

I updated the post for snippets.

[changeset-bot]

⚠️ No Changeset found

Latest commit: 18df019

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR