add minimal screen cheatsheet

cheatsheets/screen

@@ -0,0 +1,11 @@
+# Start a new named screen session:
+screen -S session_name
+
+# Detach from the current session:
+Press Ctrl+A then press d
+
+# Re-attach a detached session:
+screen -r session_name
+
+# List all screen sessions:
+screen -ls