Extended examples as a section of examples

[germa89]

As requested in #1019 I have decided to move that section to the Example section.

Results

Things to notice

• Now, in the directory /doc/source/examples/ there is two folders: examples where all the dynamic examples are located during the building process, and extended_examples where the static extended examples are located. I have modified the MakeFile to just delete /doc/source/examples/examples/. But it is good to notice.

• I also renamed some example sections (titles)

• I personally believe we should make all the TechDemos statics. DONE.

== Edit ==
This PR closes #1019.

[codecov]

Codecov Report

Merging #1029 (312ebb0) into main (d4800e0) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1029      +/-   ##
==========================================
- Coverage   71.33%   71.32%   -0.02%     
==========================================
  Files          43       43              
  Lines        6085     6086       +1     
==========================================
  Hits         4341     4341              
- Misses       1744     1745       +1     

[akaszynski]

Fully agree with this approach.

[germa89]

I have decided to move techdemos to another section and put both we have together. This should force me to do more techdemos.

I also made techdemo20 static.

[pmaroneh]

Just two small suggestions that can be ignored if too much trouble:

• On the left side panel, could we have some sort of hierarchy? Ie have some form of titles and then below the title the examples belonging to this section?
• Could we have a way to make the "Contributing" example either at the top or at the end of the list ? It would make it easier to find.

[akaszynski]

This was a complicated one.

The issue is that sphinx is reporting duplicated labels because it reads through every file matching *.rst, which means that when we include the file with .. include:: gallery_examples/index.rst, it gets read twice.

Normally, we could just rename it to .txt, but since sphinx-gallery generates an index.rst and it's not an option to change it, we have to ignore it with:
https://github.com/pyansys/pymapdl/blob/c49142a963c459ec43b042241ac22561052ee6c2/doc/source/conf.py#L135-L141

[akaszynski]

Finally!

Because we made major changes, our doc cache needed to be cleared. I did this by bumping:
https://github.com/pyansys/pymapdl/blob/312ebb0ec1d8d55bef864584ee925e26e6593fb8/pyproject.toml#L8