#nojira Add v6.8 as a heading in changelog

[x-eun]

Description

In the Changelog, v6.8 is currently formatted as a regular paragraph instead of a heading. This PR adds the H1 formatting to it to make it consistent with other versions.

Fixes # (issue)

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Document change (fix typo or modifying any markdown files, code comments or anything in the examples folder only)

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New Feature Submissions

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Changes to Core Features

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