Create system-info cache directory in WSL

system-info/system-info-WSL.sh

@@ -3,6 +3,11 @@
 cache_dir=~/.cache/tmux
 cache_file=$cache_dir/system-info
 
+# Make sure the output directory exists.
+if [ ! -d $cache_dir ]; then
+  mkdir -p $cache_dir
+fi
+
 while true; do
   # Assumes OpenHardwareMonitor is has the Remote Web Server enabled on port
   # 8085 of the Windows host. In WSL2 the Windows host IP is accessible using