[support.limits.general] Fix typo: '<forwardlist>' should be '<forward_list>'

Author: tkoeppe

source/support.tex

@@ -590,7 +590,7 @@
 \defnlibxname{cpp_lib_hypot}                                & \tcode{201603L} &
   \tcode{<cmath>} \\ \rowsep
 \defnlibxname{cpp_lib_incomplete_container_elements}        & \tcode{201505L} &
-  \tcode{<forwardlist>} \tcode{<list>} \tcode{<vector>} \\ \rowsep
+  \tcode{<forward_list>} \tcode{<list>} \tcode{<vector>} \\ \rowsep
 \defnlibxname{cpp_lib_integer_sequence}                     & \tcode{201304L} &
   \tcode{<utility>} \\ \rowsep
 \defnlibxname{cpp_lib_integral_constant_callable}           & \tcode{201304L} &