Manual: variable SIGWINCH has no definition

[Christophe Jarry]

Dear developers,

While reading
http://www.gnu.org/software/bash/manual/html_node/Bash-Variables.html#index-COLUMNS-179
today, I found variable SIGWINCH has no definition.

Please add the definition of the variable SIGWINCH in
http://www.gnu.org/software/bash/manual/html_node/Bash-Variables.html.

Thanks,

Christophe