docs: fix sign of online softmax rescaling factors

docs/20250422-new-kernel-deep-dive.md

@@ -27,10 +27,10 @@ Our solution involves an additional mathematical transformation beyond FlashAtte
 0. Maintain a running max $m$ (initialized to $-\infty$, shared between the two warpgroups) and output matrices $\vec o_L, \vec o_R$ (initialized to 0).
 1. [0] Compute $`\vec p_0 = \vec q K_0^\intercal / qk\_scale`$.
 2. [1] Compute $`\vec p_1 = \vec q K_1^\intercal / qk\_scale`$.
-3. [0] Compute $mp_0 = \max(\vec p_0)$, $`m\_new_0 = \max(m, mp_0)`$, and $`scale_0 = \exp(m\_new_0 - m)`$. Update $`m \gets m\_new_0`$.
+3. [0] Compute $mp_0 = \max(\vec p_0)$, $`m\_new_0 = \max(m, mp_0)`$, and $`scale_0 = \exp(m - m\_new_0)`$. Update $`m \gets m\_new_0`$.
 4. [0] Perform softmax on $\vec p_0$: $`\vec p_0 \gets \exp(\vec p_0 - m\_new_0)`$.
 5. [0] Update $\vec o_L \gets \vec o_L \cdot scale_0 + \vec p_0 V_{0L}$.
-6. [1] Compute $mp_1 = \max(\vec p_1)$, $`m\_new_1 = \max(m, mp_1)`$, and $`scale_1 = \exp(m\_new_1 - m)`$. Update $`m \gets m\_new_1`$.
+6. [1] Compute $mp_1 = \max(\vec p_1)$, $`m\_new_1 = \max(m, mp_1)`$, and $`scale_1 = \exp(m - m\_new_1)`$. Update $`m \gets m\_new_1`$.
 7. [1] Perform softmax on $\vec p_1$: $`\vec p_1 \gets \exp(\vec p_1 - m\_new_1)`$.
 8. [1] Update $\vec o_R \gets \vec o_R \cdot (scale_0 \cdot scale_1) + \vec p_1 V_{1R}$.
 9. [0] Update $\vec p_0 \gets \vec p_0 \cdot scale_1$.