Remove extra $ in README

Hi,

I noticed you've got a left over `$` from where you removed `$_POST` from the examples a couple of weeks ago. I've removed it in this PR.

Thanks for making and maintaining this repo

README.md

@@ -95,7 +95,7 @@ $contact = $hubSpot->crm()->contacts()->basicApi()->create($contactInput);
 
 ```php
 $newProperties = new \HubSpot\Client\Crm\Contacts\Model\SimplePublicObjectInput();
-$newProperties->setProperties($[
+$newProperties->setProperties([
     'email' => '[email protected]'
 ]);