Fix inequality in docs for div_euclid

[jturner314]

This commit fixes the statement of the inequality that the Euclidean remainder satisfies. (The remainder is guaranteed to be less than abs(rhs), not rhs.) It also rewords the documentation to make it a little easier to read.

(You might wonder why I've written abs(rhs) instead of rhs.abs(). Two reasons: first, the rem_euclid docs use abs(rhs) instead of rhs.abs(), and second, the absolute value here is the mathematical absolute value, not the the .abs() operation which may overflow.)

[rust-highfive]

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[sfackler]

Why is n changing to q?

[jturner314]

The only reason is that q makes me think of "quotient", while n is just a generic "number" in my mind. I can change it back to n if you'd prefer.

[JohnTitor]

LGTM, I also think q makes more sense here.

@bors r+ rollup

[bors]

📌 Commit 77c0a48 has been approved by JohnTitor

[bors]

⌛ Testing commit 77c0a48 with merge 7f82ddb...

[bors]

☀️ Test successful - checks-actions
Approved by: JohnTitor
Pushing 7f82ddb to master...