MAINT: remove %matplotlib inline and contents directives

[mmcky]

This PR

• [x] removes %matplotlib inline and associated figsize settings
• [x] removes contents directives as not needed
• [x] validate the preview visually (spot checking)

[mmcky]

• [x] confirm linkchecker are false positives

[github-actions[bot]]

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[mmcky]

@jstac I think this is looking good.

[jstac]

Many thanks @mmcky . If you think it's necessary please get another set of eyes to review. Otherwise please go ahead and merge.

[mmcky]

thanks @jstac I have done quite a few spot checks so I will merge.