Improve documentation on AuxKernels idaholab#29484

Author: kyriv1980

modules/subchannel/doc/content/source/auxkernels/RZQPrimeAuxPin.md

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+# RZQPrimeAuxPin
+
+!syntax description /AuxKernels/RZQPrimeAuxPin
+
+## Description
+
+<!-- -->
+
+The `RZQPrimeAuxPin` AuxKernel is used to compute the linear heat rate (w/m) on the surface of a fuel pin that is modeled with a 2D-RZ axi-symmetric mesh.
+It's a kernel that inherits from `DiffusionFluxAux` to calculate the flux, but in addition it multiplies with the pin diameter. The user needs to provide the
+diffusion coefficient and the temperature variable.
+
+## Example Input File Syntax
+
+!listing /examples/coupling/1pinSquare_thermomech_SC/one_pin_problem_sub.i block=AuxKernels language=cpp
+
+!syntax parameters /AuxKernels/RZQPrimeAuxPin
+
+!syntax inputs /AuxKernels/RZQPrimeAuxPin
+
+!syntax children /AuxKernels/RZQPrimeAuxPin