supervisor: add README and update completion (#8285)

plugins/supervisor/README.md

+# supervisor plugin
+
+This plugin adds tab-completion for `supervisord`/`supervisorctl` in [Supervisor](http://supervisord.org/).
+Supervisor is a client/server system that allows its users to monitor and control a number
+of processes on UNIX-like operating systems.
+
+To use it, add `supervisor` to the plugins array in your zshrc file:
+```zsh
+plugins=(... supervisor)
+```
+
+These scripts are from [zshcompfunc4supervisor](https://bitbucket.org/hhatto/zshcompfunc4supervisor).

plugins/supervisor/_supervisorctl

@@ -112,6 +112,13 @@ _supervisorctl_start() {
         '*::supvervisor process:_get_supervisor_procs'
 }
 
+(( $+functions[_supervisorctl_restart] )) ||
+_supervisorctl_restart() {
+    # TODO: add 'all'
+    _arguments -s \
+        '*::supvervisor process:_get_supervisor_procs'
+}
+
 (( $+functions[_supervisorctl_status] )) ||
 _supervisorctl_status() {
     _arguments \