[ci skip] Update Documentation - Pyiron release chapter

[Ovakefali13]

Relates to issue #599 and #590.

This PR is still work in progress, please feel free to add things and/or comment on things that might feel unclear.

What I changed:

• Added chapter for distribution
  • Rearanged links
  • Updated chapter structure
  • Deleted Travis
• Added chapter for Building process
  • Added steps that take place to release different distributions
• Added chapter for Github workflow
  • Added links to the different Github workflows
  • Added descriptions of Github workflows
• Added comments to the workflow files

What I still want to do:

• Add descriptions for docs.yml
• Add descriptions for notebooks.yml
• Add descriptions for pypicheck.yml
• Add descriptions for unittests.yml
• Add first sentence of documentation to each workflow
• Change from draft to PR

[Ovakefali13]

@niklassiemer While going through the workflows I noticed that some of the comments inside appear to be outdated as well. E.g.

# This workflow will install Python dependencies, run tests and lint with a variety of Python versions
# For more information see: https://help.github.com/actions/language-and-framework-guides/using-python-with-github-actions

I'm currently writing a short descripition for each of these workflows and am thinking about changing these comments with a new short sentence about what the workflow actually does. Should I open a new issue for this (and or create a new PR) or should I just do this within the current PR (seems a bit bad practice).

[niklassiemer]

You are absolutely right. The comments are from a first version of these GitHub workflows and are quite outdated. I think we started with a unittest workflow (for which the sentence is ok) and copied the workflow without changing the description.
Since this is all 'Documentation' I would be happy to simply handle your improvements within this PR. However, feel free to open a new PR to update the workflow documentation.

[niklassiemer]

Thanks a lot for updating this! I found quite some stuff where our previous documentation was to bad to get what is actually going on...

[Ovakefali13]

You are absolutely right. The comments are from a first version of these GitHub workflows and are quite outdated. I think we started with a unittest workflow (for which the sentence is ok) and copied the workflow without changing the description. Since this is all 'Documentation' I would be happy to simply handle your improvements within this PR. However, feel free to open a new PR to update the workflow documentation.

Ok i keep it here so it is simpler

[Ovakefali13]

I will add the last missing workflows until the end of this week, add the first lines of each of these to the corresponding workflow and then change the PR from draft to actual PR for final review

[niklassiemer]

I made a few corrections, but otherwise LGTM.

[niklassiemer]

One typo and then this is good to go :) Thanks!