Update some tutorial links

[dcslagel]

Description:

• Update links to the contributing-guide/dev-guide. The previous links were not found (404).
• Update link to pypi-release-checklist. The previous link no-longer exists.

Test Results:

Note: I didn't add any new tests since this pull-request is just document changes. Let me know if I should add some.

All tests for py38 succeeded. (py36 and py37 interpreters were not found).

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Let me know if this change could be accepted (or rejected) or needs some additional changes before being approved and merged.

Thank you, DC

[choldgraf]

LGTM - thanks!

[lwasser]

thank you all!!!

[dcslagel]

Thank you for accepting this pull request. :-)