Add KDE Konsole terminal to termcmd

Konsole doesn't work well with non-default Kakoune themes, so I've put it last in the list, but in case when no other terminal is available it's good to have it in the list for launching non-kakoune things, like tig

rc/base/x11.kak

@@ -13,7 +13,8 @@ A shell command is appended to the one set in this option at runtime} \
                    'mintty         -e sh -c' \
                    'sakura         -x      ' \
                    'gnome-terminal -e      ' \
-                   'xfce4-terminal -e      ' ; do
+                   'xfce4-terminal -e      ' \
+                   'konsole        -e      '; do
         terminal=${termcmd%% *}
         if command -v $terminal >/dev/null 2>&1; then
             printf %s\\n "$termcmd"