Update powi.zig to fix docstring formatting

Without this change, the docs are formatted s.t. the text "Edge case rules ordered by precedence:" is appended onto the prior line of text "Underflow: Absolute value of result smaller than 1", instead of getting its own line.
9ef2208e4bBecker A. committed on 8/25/2025, 4:51:41 PM· committed by Alex Rønne Petersenparent38173d6
1 file changedLine totals unavailable