Fix a missing transpose.

examples/step-69/doc/intro.dox

@@ -65,7 +65,7 @@ where $\mathbf{u}(\textbf{x},t):\mathbb{R}^{d} \times \mathbb{R}
 dimension. We say that $\mathbf{u} \in \mathbb{R}^{d+2}$ is the state and
 $\mathbb{f}(\mathbf{u}) \in  \mathbb{R}^{(d+2) \times d}$ is the flux of
 the system. In the case of Euler's equations the state is given by
-$\textbf{u} = [\rho, \textbf{m},E]^{\top}$: where $\rho \in \mathbb{R}^+$
+$\textbf{u} = [\rho, \textbf{m}^\top,E]^{\top}$: where $\rho \in \mathbb{R}^+$
 denotes the density, $\textbf{m} \in \mathbb{R}^d$ is the momentum, and $E
 \in \mathbb{R}^+$ is the total energy of the system. The flux of the system
 $\mathbb{f}(\mathbf{u})$ is defined as