Add documentation about using US-English

What does this MR do?

Add documentation about using US-English

Are there points in the code the reviewer needs to double check?

Make sure this is what we want to move forward with.

Why was this MR needed?

Consistency

Screenshots (if relevant)

None

Does this MR meet the acceptance criteria?

Yes

What are the relevant issue numbers?

Closes #40675 (closed)