Fixing nbqa linting for latest notebook

[axsaucedo]

What this PR does / why we need it:

Fixes broken tests:

• Python lint with noqa
• Docs lint with broken link
• Docs build with unreferenced link

Running nbqa to fix the lint of relevant notebooks.

nbqa black \
        ../ --nbqa-exclude "(proto|seldon_core/proto/|.eggs|.tox|_README\.ipynb)"

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

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[seldondev]

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[axsaucedo]

All tests fixed, merging