docs: removing duplicated step

[bzenky]

Description

Looking through docs I found a duplicated step

Specific Changes proposed

Remove duplicated step in multiple-alternative-audio-tracks doc

Requirements Checklist

• Feature implemented / Bug fixed
• If necessary, more likely in a feature request than a bug fix
  • Unit Tests updated or fixed
  • Docs/guides updated
  • Example created (starter template on JSBin)
• Reviewed by Two Core Contributors

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[adrums86]

Good catch, thanks for this!

[welcome]

Congrats on merging your first pull request! 🎉🎉🎉