overall documentation alignment

[AlexTheLion123]

Some of the docs use old, outdated code. Update them to all use a standard template for the notebooks.

TODO: add more detail

[miohtama]

Let's close this and fix this in a next version of backtesting framework, with more incompatible rewrites.

[AlexTheLion123]

• Should be closer to complete with https://github.com/tradingstrategy-ai/docs/pull/39
• Still waiting for next version of backtesting framework to complete fully

[AlexTheLion123]

• check order of template (should summary stats be shown before visuals?)
• check everything currently included is relevant
• check if anything else needs to be added.