Removed more rogue characters from keyword defintiions

src/drr/DynamicReferenceRestraining.cpp

@@ -250,7 +250,7 @@ void DynamicReferenceRestraining::registerKeywords(Keywords &keys) {
   keys.add("optional", "KAPPA", "specifies that the restraint is harmonic and "
            "what the values of the force constants on "
            "each of the variables are (default to "
-           "\\f$k_BT\\f$/(GRID_SPACING)^2)");
+           "k_BT/(GRID_SPACING)^2)");
   keys.add("compulsory", "TAU", "0.5", "specifies relaxation time on each of "
            "variables are, similar to "
            "extended Time Constant in Colvars");