Replace a block with a picture

[psohm]

Description

For those who wants to use the templace processor to insert picture in the docs, here a piece of code found on the differents issues / stackoverflow.
Hope it will be integrated in the code.

Fixes #532 / #708 / #260

Checklist:

• I have run composer run-script check --timeout=0 and no errors were reported
• The new code is covered by unit tests (check build/coverage for coverage report)
• I have updated the documentation to describe the changes

[troosan]

I merged #1170 which is doing the same. Feel free to open a new PR if features are missing