Update Publications.md

[stuartmuldrew]

Adding PROCESS publications not listed in publications.md:

Overview of European efforts and advances in Stellarator power plant studies
F. Warmer, J. Alguacil, D. Biek, T. Bogaarts, G. Bongiovì, V. Bykov, J.P. Catalán, R.K. Duligal, I. Fernández-Berceruelo, S. Giambrone, C. Hume, M. Hrecinuc, R. Kembleton, J. Lion, T. Lyytinen, J.A. Noguerón Valiente, I. Palermo, V. Queral, D. Rapisarda, W.J. Rutten, L. Sanchis, X. Sarasola, K. Sedlak, A. Snicker, D. Sosa, F.R. Urgorri
Fusion Engineering and Design 202 (2024) 114386

[stuartmuldrew]

Also adding:

The Influence of Confinement Scaling on Spherical Tokamak Power Plant Design and Performance
C. Ashe, S.I. Muldrew
IEEE Transactions on Plasma Science (Early Access)