Webhook registration failure error message not detail enough.

[MadhurangaWije]

Description:
Error message which comes when webhook registration failed, is not detailed enough.

Steps to reproduce:
Webhook registration fails in GitHub when trying to register more than 20 webhooks. at that time the following log message comes.

Affected Versions:
GitHub Connector v0.99.14

OS, DB, other environment details and versions:
Ballerina Swan Lake Alpha 5

Suggested Labels (optional):
module/websub

Suggested Assignees (optional):
@ayeshLK