supervisord & supervisorctl: add page (#1226)

pages/common/supervisorctl.md

@@ -0,0 +1,24 @@
+# supervisorctl
+
+> Supervisor is a client/server system that allows its users to control a number of processes on UNIX-like operating systems.
+> Supervisorctl is the command-line client piece of the supervisor which provides a shell-like interface.
+
+- Start/stop/restart a process:
+
+`supervisorctl {{start|stop|restart}} {{process_name}}`
+
+- Start/stop/restart all processes in a group:
+
+`supervisorctl {{start|stop|restart}} {{group_name}}:*`
+
+- Show last 100 **bytes** of process stderr:
+
+`supervisorctl tail -100 {{process_name}} stderr`
+
+- Keep displaying stdout of a process:
+
+`supervisorctl tail -f {{process_name}} stdout`
+
+- Reload process config file to add/remove processes as necessary:
+
+`supervisorctl update`