app_token_auth: add description to ks in step 3
app_token_auth: add description to ks in step 3

kaltura/developer-platform,kaltura/developer-platform,kaltura/developer-platform,kaltura/developer-platform,kaltura/developer-platform,kaltura/developer-platform,kaltura/developer-platform,kaltura/developer-platform,kaltura/developer-platform,kaltura/developer-platform