Tutorial should be conformed to the Spyder Docs style guide

[CAM-Gerlach]

Problem Description

As a follow-on to #7641 / #7643 we should have our tutorial match our docs by conforming to the same style guide, which will both further enhance its appearance and externel consistency, and also improve maintainability and internal consistency between them. Basic plan, inspiried by spyder-ide/spyder-docs#13 :

• Harmonize line breaks to one per sentence to make both editing and reviewing changes much easier, and git much cleaner and more effective
• Change implicit to explicit references
• Use consistent marker characters, naming scheme, and structure for titles, headings and subheads
• Harmonize formatting of elements/directives to conform to style guide
  • All bullets to *
  • i.e. -> i.e.
  • File names/paths
  • Keyboard shortcuts
  • GUI elements
  • Menu/preference selections
  • Code blocks
• Restructure: Bullets vs. steps vs. prose