Allow breaking cross-reference of tokens in a productionlist

[StanFromIreland]

Before:

After:

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📚 Documentation preview 📚: https://cpython-previews--148845.org.readthedocs.build/

[encukou]

I'll find the relevant rules to link instead, when I'm at a desk.
(The rule names are different between the docs & the grammar; I'm slowly syncing them but in the mean time it's a bit confusing.)

If you do want to to suppress the linking, you can omit the backquotes entirely -- the literal node this PR adds doesn't have semantic meaning. Don't do that here though.

[encukou]

I sent #149811 for these.