Update INSFVTKEDSourceSink.md idaholab#27800 idaholab#27887 idaholab#27888

Author: freiler

modules/navier_stokes/doc/content/source/fvkernels/INSFVTKEDSourceSink.md

@@ -29,6 +29,7 @@ where:
 
 - $C_{2,\epsilon} = 1.92$ is a closure parameter,
 - $\epsilon$ is the solution variable, i.e., the dissipation rate of the turbulent kinetic energy,
+- $k$ is the turbulent kinetic energy,
 - $t_k = \frac{k}{\epsilon}$ is the turbulent time scale; if the [!param](/FVKernels/INSFVTKEDSourceSink/linearized_model) is `true`, this timescale is computed from the previous iteration; if [!param](/FVKernels/INSFVTKEDSourceSink/linearized_model) is `false`, in a nonlinear solve, this timescale is aded to the Jacobian.
 
 ## Wall formulation: