fix: add version field to /api/v1/server response

Include globals.Version in the server info JSON response and update
README documentation to reflect the new field.

internal/handlers/api.go

@@ -2336,9 +2336,10 @@ func (hdlr *Handlers) HandleServerInfo() http.HandlerFunc {
 		}
 
 		hdlr.respondJSON(writer, request, map[string]any{
-			"name":  hdlr.params.Config.ServerName,
-			"motd":  hdlr.params.Config.MOTD,
-			"users": users,
+			"name":    hdlr.params.Config.ServerName,
+			"version": hdlr.params.Globals.Version,
+			"motd":    hdlr.params.Config.MOTD,
+			"users":   users,
 		}, http.StatusOK)
 	}
 }