update to README for API client class

phpapi/README.md

@@ -108,7 +108,7 @@ $results   = $unifidata->list_alarms(); // returns the alarms in a PHP array
 ...
 ```
 
-NOTE: $site_id is the 8 character short site "name" which is visible in the URL when managing the site in the UniFi controller:
+**NOTE:** $site_id is the 8 character short site "name" which is visible in the URL when managing the site in the UniFi controller:
 
 ```
 https://<controller IP address or FQDN>:8443/manage/site/jl3z2shm/dashboard