docs: fix grammar in changelog

[benmccann]

Description

Three changes to this sentence:

• "since" should refer to an effect of the action
• the double loading happens because "a and b" load it. "but" indicates opposition, but the two both need to happen for there to be double loading, so there's no opposition
• use an em dash to separate example

Additional context

The rest of the changelog reads well to me

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Before submitting the PR, please make sure you do the following

• Read the Contributing Guidelines.
• Read the Pull Request Guidelines and follow the Commit Convention.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Ideally, include relevant tests that fail without this PR but pass with it.

[patak-dev]

Thanks a lot Ben! 🙏🏼