Separate tutorials by levels and create the gallery of them

[Mr-Geekman]

🚀 Feature Request

We should separate our tutorials by level of expertize.

We could also create some kind of gallery of them on the Tutorials page like in smth like:

• https://www.sktime.net/en/stable/index.html
• https://www.sktime.net/en/stable/examples.html
• Or just nicely order them

Proposal

Separate tutorials by level of expertize.

Basic:

• get_started
• backtest
• eda

Intermediate:

• exogenous_data
• NN_examples
• ensembles
• outliers
• automl
• clustering
• feature_selection
• forecasting_strategies

Advanced:

• custom_transform_and_model
• inference
• hierarchical_pipeline
• forecasting_interpretation
• classification

Creating a gallery on Tutorials page. Options:

• https://www.sktime.net/en/stable/index.html
• https://www.sktime.net/en/stable/examples.html
• Just nicely order them

We should probably give a short description of each tutorial in this gallery.

To discuss:

• Is this division ok?
• How to create gallery?
• Do we want to rename tutorials according the the levels?
  • Yes, let's rename them.

Test cases

No response

Additional context

No response