Fix a missing transpose.

[bangerth]

In this place, we create a column vector by transposing a vector written as a row vector -- except that one component of the row vector is a column vector.

@jerett-cc FYI

[marcfehling]

You will also need to adjust this line

dealii/examples/step-69/doc/intro.dox

Line 132 in 635a114

[\rho, \textbf{m},E]^{\top} \in \mathbb{R}^{d+2} \, \big |

[bangerth]

Good catch -- so fixed!