Update French 2.3 instruction to match TM4

[jarmokivekas]

Currently section 2.3 instructions are written for TM3, while screenshots have been updated to TM4, so it may be slightly confusing.

Main differences that stood out to me:

• The search bar is no longer on the left:

  https://github.com/hotosm/toolbox/blame/master/content/fr/pages/digitization-and-editing/2.3-Working-with-the-HOT-Tasking-Manager.md#L72

• Task square color legend has changed:

  https://github.com/hotosm/toolbox/blame/master/content/fr/pages/digitization-and-editing/2.3-Working-with-the-HOT-Tasking-Manager.md#L101-L107

• Button labels for staring mapping and the editor selection process has changed a little:

  https://github.com/hotosm/toolbox/blame/master/content/fr/pages/digitization-and-editing/2.3-Working-with-the-HOT-Tasking-Manager.md#L109-L115