4.x Review/update CORS examples and docs now that SE CORS is automatically added as a server feature

[tjquinno]

Environment Details

• Helidon Version: 4.0.0
• Helidon SE or Helidon MP SE
• JDK version:
• OS:
• Docker version (if applicable):

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Problem Description

Helidon CORS was turned into a server feature late in 4.0.0, introducing changes in behavior. For example, Helidon now adds CORS automatically if it is on the class path with no need for the developer to explicitly add it to the server or routing as was required in 3.x.

• Update CORS documentation
• Double-check CORS-related examples