Remove "img not found" and inform users of "coming soon" docs

[samamou]

It seems that certain pages or sections are auto-generated but lack content. In these cases, users should be informed that the content is coming soon to avoid confusion

• Remove h1 from pages that currently have no content.

• Insert a "Coming Soon" message to indicate that content will be available in the future.
  <p>Documentation is under construction! 🚧</p>

Example

https://ossia.io/score-docs/processes/ai-recognition.html
https://ossia.io/score-docs/processes/computer-vision-utilities.html