fix: remove new method from koa docs

Author: AbhiPrasad

docs/platforms/javascript/common/configuration/integrations/koa.mdx

@@ -22,7 +22,7 @@ The `koaIntegration` adds instrumentation for the Koa framework to capture spans
 
 ```JavaScript
 Sentry.init({
-  integrations: [new Sentry.koaIntegration()],
+  integrations: [Sentry.koaIntegration()],
 });
 ```