Section about example building for doc in contribution

[germa89]

The documentation does not specify how the examples are build (tools, directories, types, etc).

I would like this information to be added to the docs. This documentation should include:

Notes

There are three types of examples:

• Dynamic (based on a python file). Run under 3 minutes.
  There are in examples directory in the repo.
  Example: https://github.com/pyansys/pymapdl/blob/main/examples/00-mapdl-examples/2d_plate_with_a_hole.py

• Static (based on RST file)
  They are in the doc\source directory.
  Example: https://raw.githubusercontent.com/pyansys/pymapdl/main/doc/source/examples/extended_examples/Krylov/krylov_example.rst

• Semi-dynamic (an RST file which execute python code).
  Example:
  https://raw.githubusercontent.com/pyansys/pymapdl/main/doc/source/examples/technology_showcase_examples/techdemo-28/ex_28-tecfricstir.rst

.. jupyter-execute:: 
    :hide-code:

    ## figure 28.5
    mapdl.allsel("all")
    mapdl.esel('s', 'mat', '', 2)
    mapdl.nsle('s')

To install the libraries for running the documentation tools do:

pip install -r requirements/requirements_docs.txt

The Sphinx configuration is in the file conf.py in doc/source.

To run the sphinx tool:

doc\make.bat html

The new section should be probably around here:
https://mapdl.docs.pyansys.com/contribution_and_api/index.html#viewing-pymapdl-documentation

[germa89]

Add also piracy policy somewhere.

[germa89]

Updating issue text