docs(integrations): Add SpeedCurve to "Lighthouse Integrations"

[wildlyinaccurate]

Summary

SpeedCurve just added support for Lighthouse, and we thought it was worth adding to the Lighthouse Integrations section!

Relevant announcement blog post: https://speedcurve.com/blog/lighthouse-scores-now-available/

[googlebot]

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[wildlyinaccurate]

Signed the CLA!

[googlebot]

CLAs look good, thanks!

[brendankenny]

nice!

[brendankenny]

I think we're alphabetizing these to keep things "fair"

[wildlyinaccurate]

Updated - thanks!