Fixed README image integration

[starlord-daniel]

Somehow the image 14 is not correctly rendered on the website: https://azure-samples.github.io/azureiotlabs/EventGrid/ I removed the empty parentheses in an attempt to fix it.

Purpose

Fixing an image reference in README for https://azure-samples.github.io/azureiotlabs/EventGrid/

Does this introduce a breaking change?

[ ] Yes
[x] No

## Pull Request Type
[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[x] Documentation content changes
[ ] Other... Please describe:

How to Test

What to Check

If you include the change, the image 14 ![Integrated with IoTHub](images/14_empty_event_subscription.png “”) on https://azure-samples.github.io/azureiotlabs/EventGrid/ should be visible. Currently it shows:

Click on Event Subscription


Copy the URL from previous steps into Subscriber Endpoint and click create