add health endpoint for monitoring

src/qrzws/main.go

@@ -38,6 +38,9 @@ func RunServer(config config.Config) (err error) {
 	e.Renderer = builtTemplates
 
 	e.GET("/", p.Index)
+	e.GET("/health", func(c echo.Context) error {
+		return c.String(http.StatusOK, "OK")
+	})
 	e.GET("/static/*", func(c echo.Context) error {
 		return static.GetStatic(&root.Files, c)
 	})