feat: Flag mixed up irregular plurals

## Description

Some words with irregular plurals are not very common or one form is much more common than the other so people use the wrong form.

## Examples

- ... late to get Motorola/Freescale/NXP to issue **an errata** → ... **an erratum** (or **some errata**)

## Notes

This is a distinct issue from using a regular plural instead of the traditional irregular one like forums/fora