fix rendering of 5e-5

Author: JoshuaLampert

docs/src/overview.md

@@ -182,7 +182,7 @@ This creates the following figure:
 ![analysis callback](analysis_callback.png)
 
 You can see that the linear invariants ``\int_\Omega\eta\textrm{d}x`` and ``\int_\Omega v\textrm{d}x`` are indeed conserved exactly. The entropy, however, starts
-growing at around ``t = 17``  and rises up to approximately ``5e-5``. This is because of the fact that, during the time integration, a nonlinear invariant is not
+growing at around ``t = 17``  and rises up to approximately `5e-5`. This is because of the fact that, during the time integration, a nonlinear invariant is not
 necessarily conserved, even if the semidiscretization conserves the quantity exactly. How to obtain a fully-discrete structure-preserving numerical scheme is explained
 in the following section.