updates needed to prepare for release

[valentina-s]

• doc reorganization (1 level up)
• adding automatic version reading
• Readme now contains the pypi installation instructions
• rerender all notebooks
• one-sided bound for pandas version
• tested on test-pypi: https://test.pypi.org/project/echoshader/

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[valentina-s]

@leewujung I think we can release this version.