[Tutorials] Update tutorial documentations

[Maghoumi]

Description

• Add a README file for the tutorials.
• Add a table of all tutorials, along with a brief description of each one.
• Add a structure outline to the README file of the SDG tutorial to make it more accessible.
• Add a block diagram to the SDG tutorial further clarify the pipeline.

Checklist

• [x] I am familiar with the Contributing Guide.
• [x] New or Existing tests cover these changes.
• [x] The documentation is up to date with these changes.