Book will not build with MuTalk chapter addition

[AndrzejProchyra]

Since #21 was merged, it is no longer possible to build the PDF book. I have been building it in my fork, due to the disabled workflow in this repo.

The first problem is that index.md has an incorrect reference to the MuTalk chapter file:

<!inputFile|path=Chapters/Mutalk/Mutalk.md!>

This results in the following error:

MicResourceReferenceError: The Microdown file at "/home/runner/work/Booklet-TestingInPharo/Booklet-TestingInPharo/Chapters/Mutalk/Mutalk.md" is not found
(See build)

Presumably the refrerence should be:

<!inputFile|path=Chapters/MuTalk/MuTalk.md!>
(note the Pascal case naming)

Correcting this leads to further errors that the following referenced files are missing:

• /Chapters/MuTalk/figures/Operators tab1.pdf
• /Chapters/MuTalk/figures/Operators tab2.pdf
• /Chapters/MuTalk/figures/MyVehicleMatrixCropped.pdf
• /Chapters/MuTalk/figures/MyVehicleHeatmapCropped.pdf
  (See build)

[Ducasse]

Thanks for bug issue. @guillep will handle this.