Remove MV2 code from "Create an extension tutorial, part 2"

[bhuvanapriyap]

Rendered article for review:

• Create an extension tutorial, part 2
  • https://review.learn.microsoft.com/microsoft-edge/extensions-chromium/getting-started/part2-content-scripts?branch=pr-en-us-3278
  • Before/Live
  • Removed MV2 code.
  • Removed MV3/MV2 tabset tagging.
  • Removed "The source code has been updated from Manifest V2 to Manifest V3."
  • Also:
    • Reformatted "you'll do step 1, you'll later do step 3, but for now do step 2" as numbered list.
    • Lowercased "the Extension".
    • Added See also h2 section.

AB#54090967

[mikehoffms]

LGTM - Writer/Editor

[learn-build-service-prod]

Learn Build status updates of commit 24fd8d4:

✅ Validation status: passed

File	Status	Preview URL	Details
microsoft-edge/extensions-chromium/getting-started/part2-content-scripts.md	✅Succeeded	View

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[bhuvanapriyap]

LGTM - PM