Vale rule to spell out numbers under 10 (if that is the guidance for your product)

[rohennes]

Is your feature request related to a problem? Describe.
Product docs can choose to spell out numbers under 10, or use the numerals 1-9.
https://www.ibm.com/docs/en/ibm-style?topic=measurement-numerals-versus-words

Describe the solution you'd propose
For teams that use spelled out numbers, flag on numerals 1-9. It may be a bit tricky to avoid false positives, for example 8 million, but worth a look.