fix typo in book example link #13

Job	Run time
Code Coverage	10s
Tests (windows-latest, chrome, plotly_ndarray,plotly_image,static_export_chromedriver,debug)	6m 5s
Clippy	4m 8s
Tests (ubuntu-latest, chrome, plotly_ndarray,plotly_image,static_export_default,debug)	3m 4s
Tests (ubuntu-latest, firefox, plotly_ndarray,plotly_image,static_export_geckodriver,static_expor...	2m 57s
semver	51s
Rustfmt	17s
Build Book	3m 32s
Tests (macos-latest, chrome, plotly_ndarray,plotly_image,static_export_default,debug)	2m 18s
Build Examples (customization/consistent_static_format_export)	1m 24s
Build Examples (financial_charts)	25s
Build Examples (subplots)	35s
Build Wasm Examples (callback-example)	54s
Build Examples (custom_controls)	37s
Build Wasm Examples (basic)	54s
Build Examples (themes)	31s
Build Examples (maps)	45s
Build Examples (ndarray)	28s
Build Examples (basic_charts)	37s
Build Examples (kaleido)	1m 28s
Build Examples (customization/density_mapbox_example)	34s
Build Examples (shapes)	35s
Build Examples (customization/multiple_plots_example)	34s
Build Examples (3d_charts)	38s
Build Examples (images)	46s
Build Examples (statistical_charts)	37s
Build Examples (scientific_charts)	41s
	36m 25s

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