CMCL-0000: Docs - Moved up the note about videos

[sebastienduverne]

[Delete any line or section that does not apply]

Purpose of this PR

DOCATT-8058 - User feedback: videos are old (but we know it)

• Moved up the existing note (which mentions the YouTube videos are old but still show interesting concepts) to make it more visible and bring more awareness of that state to the reader.
• Slightly changed the first words to make the note more introductive.

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Additional details and impacted files

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