I'm using Content-Security-Policy (CSP) on my website. And have setup CSP as below as per mentioned at the google developers documentation (Frequently Asked Questions  |  reCAPTCHA  |  Google for Developers😞

- script-src https://www.google.com/recaptcha/, https://www.gstatic.com/recaptcha/
- frame-src https://www.google.com/recaptcha/, https://recaptcha.google.com/recaptcha/

But browser devtools console indicated that is an error related to CSP occurred which related to CSP's directive "connect-src". But as I find thru the developer's documentation, can't find any document mentioned that we need to setup for "connect-src" as well. 

My question is that is it necessary to setup CSP's directives "connect-src"? If yes, is there any document highlighted about it?