[Doc/RelPermUdell] Moved the cited reference to bibliography

Documentation/bibliography/other.bib

@@ -198,3 +198,14 @@ year = {2008},
 doi = {10.1680/geot.2008.58.3.157},
 URL = {https://doi.org/10.1680/geot.2008.58.3.157}
 }
+
+@article{udell1985heat,
+  title={Heat transfer in porous media considering phase change and capillarity—the heat pipe effect},
+  author={Udell, Kent S},
+  journal={International Journal of Heat and Mass Transfer},
+  volume={28},
+  number={2},
+  pages={485--495},
+  year={1985},
+  publisher={Elsevier}
+}

MaterialLib/MPL/Properties/RelativePermeability/RelPermUdell.h

@@ -20,11 +20,8 @@ class Medium;
 class Phase;
 class Component;
 /**
- * A simple relative permeability function as used in
- *
- *        Kent S Udell. "Heat transfer in porous media considering phase change
- *        and capillarity-the heat pipe effect".In:International Journal of Heat
- *        and Mass Transfer 28.2 (1985), pp. 485-495
+ * A simple relative permeability function proposed by
+ * Kent S Udell \cite udell1985heat.
  *
  *  Definition:
  *          \f[ k_{\text{rel}}^{\alpha}