Add example notebooks to docs

[liamhuber]

For rendering on readthedocs

[github-actions]

👈 Launch a binder notebook on branch pyiron/pyiron_ontology/docs_notebooks

[codacy-production]

Coverage summary from Codacy

See diff coverage on Codacy

Coverage variation	Diff coverage
✅ +0.00% (target: -1.00%)	∅

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (96afa88)	459	418	91.07%
Head commit (0ba5375)	459 (+0)	418 (+0)	91.07% (+0.00%)

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#37)	0	0	∅ (not applicable)

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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_{You may notice some variations in coverage metrics with the latest Coverage engine update. For more details, visit the documentation}

[liamhuber]

They render OK, but sphinx parses each notebook heading as a full heading; I'd like to move them each to their own level so that notebook sub-headings get parsed sensibly. Alternatively maybe a thumbnail gallery is the way to go

[liamhuber]

I like the gallery much better, but am having trouble getting the default thumbnail to register

[liamhuber]

Good enough. Just need to be able to see it on the white background now.