Mark experimental bricks

[twschiller]

Context

• Some bricks are advance/rely on experimental features
• Some new users are trying to use these and getting stuck

Discussion

• Approaches to marking as experimental:
  • Add [Experimental] prefix on the brick title. We've been marking old/outdated bricks using [Deprecated] so this follows that naming approach

Bricks to Mark

• [X] Component Reader: https://github.com/pixiebrix/pixiebrix-extension/pull/4075

Coordination

• As we mark bricks, we need to ensure we're not directing people them in tutorials