Update sample to include references

Author: ktaletsk

sample.tex

@@ -22,6 +22,7 @@ \section{Introduction}
 \begin{equation}
     \rho \left( \frac{\partial \mathbf{u}}{\partial t} + \mathbf{u} \cdot \nabla \mathbf{u} \right) =
     -\nabla P + \eta \nabla^2 \mathbf{u} + \rho \mathbf{g}.
+\label{eq:Navier–Stokes}
 \end{equation}
 \\
 \\
@@ -36,6 +37,8 @@ \section{Introduction}
   \end{tabular}
 \end{center}
 
+We can reference equations by their numbers, i.e. Equation (\ref{eq:Navier–Stokes}).
+
 \subsection{We can add new subsections}
 And we can include images, such as the Jupyter logo:
 \begin{center}