Improve the coherence between all the notebooks

[Philanoe]

Some notebooks can be improved to be more coherent with each other, in term of structure and format.

• Using the same wording as section name. Ex : using Part 1, Part 2, Part 3 all along a course, instead of using Part in one notebook and Section in another.
• When possible, keep the same part number for the same kind of content. Then, the students get used to this structure and can better concentrate on the technical parts of the courses.
• Checking the consistency of the format between each section, sub-section, etc. The best would be to start by \<h1>, and go down to \<h3> or \<h4> (# to ###).
• Some unexpected empty lines can be found in some code cells

I am going to work on week 1 notebooks and propose my modifications on DL201 cohort 7 branch. If my modifications are accepted by the community, we could use the structure of one of them to create a course notebook "pattern", useful to fix the notebooks format and make future courses faster to write (filling the holes), on condition that :

• this kind of pattern was not already present in a unpackAI repository.
• nobody thinks that fixing the notebooks format would seriously affect the creativity of the course designers

[jamescavanagh]

Yes, this pattern is a good idea.

I had tried to impliment a very similar system, and this is aligned with it if not almost the same.