Mark system as GA

[fearful-symmetry]

The system integration was technically ga'ed with 1.0.0, but I never changed the actual release tag to GA. I don't think we need to bump the version, as this was technically part of 1.0.0

What does this PR do?

This bumps the version flag in 1.0.0

Checklist

• I have reviewed tips for building integrations and this pull request is aligned with them.
• I have added an entry to my package's changelog.yml file.

[elasticmachine]

Pinging @elastic/integrations (Team:Integrations)

[elasticmachine]

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• Start Time: 2021-08-02T20:29:23.579+0000

• Duration: 13 min 13 sec

• Commit: 01686dd

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[EricDavisX]

lgtm; should we not add the version bump in?

[fearful-symmetry]

@EricDavisX Yah, that's what I wasn't sure about. technically the version was "bumped" with 1.0.0, but this is also a docs change, so we might want to do it anyway?

[EricDavisX]

thanks - seems a good way to go. points for the changelog entry, too! :)