feat: add nginx:reload command

Reloads the nginx server config after validating it with `nginx -t`. Useful for picking up changes to globally managed nginx configs without restarting the running process.

plugins/nginx-vhosts/help-functions

@@ -32,6 +32,7 @@ fn-help-content() {
     nginx:report [<app>] [<flag>], Displays an nginx report for one or more apps
     nginx:set <app> <property> (<value>), Set or clear an nginx property for an app
     nginx:show-config <app>, Display app nginx config
+    nginx:reload, Reloads the nginx server config
     nginx:start, Starts the nginx server
     nginx:stop, Stops the nginx server
     nginx:validate-config [<app>] [--clean], Validates and optionally cleans up invalid nginx configurations