See parent ticket for other requirements for a larger ticket.

Here's notes I originally had in the description, which I should also reconcile with the parent ticket:

• The list of spellings and suggested corrections should be configurable on-wiki
• The on-wiki configuration is documented on-wiki
• On-wiki configuration lints or post-process to ensure word lists remain sorted
• The configuration format should not be British English specific, instead allowing word mappings for any given category
• Conflicts when a page has multiple categories should be resolved in some way: perhaps with priority or offering a union of all matching options
• The "deep" level of the configuration mapping between words must be as straightforward as possible for an end user to edit in JSON, ie, try to keep to "match": "replacement", lines. Consider the experience in on-wiki configuration editors.
• The feedback message should be configurable, and should be able to link to documentation
• The configuration format should have a version number
• Consider future expansion: this could readily be adapted to have more complex rules, wiki-wide defaults, other rules for specific words (banning slurs, for example), different message sets, etc.
• Consider user experience for such an upgrade process: do we run a grand script to update the format for everyone, do we let individual wikis update the format in one go, or do we version each rule so each one can be handled as the need arises?

Related to T391713

Related: we can decide whether to run a check based on categories: T347775: Implement edit check configuration setting to specify categories it'll apply within

Turns out this is (almost) pure TextMatchEditCheck and I've been overthinking. See parent.