[Docs] Document new macros

docs/parts/reference.tex

@@ -78,6 +78,7 @@ These commands have to be executed outside the math environment.
     \item \verb|\tct| Time complexity in \tct{}-notation (average case)
     \item \verb|\tco| Time complexity in \tco{}-notation (worst case / upper bound)
     \item \verb|\tcl| Time complexity in \tcl{}-notation (best case / lower bound)
+    \item \verb|\t[R, C, N]| Simply prints a capital R, C or N in math mode as normal text. So e.g. use $\tR$ to print an R
 \end{itemize}
 
 \fhlc{Aquamarine}{Algorithms}