[ITB-2102, ITB-2116] Configurable SOAP and REST API test service callbacks and callback API keys

Author: costas80

gitb-ui/conf/health/testServiceCallbacks/info.md

@@ -1,4 +1,4 @@
-Callbacks from custom test services are **enabled** but without requiring valid **API keys** to be provided. Such callbacks are made during test sessions to:
+Callbacks from [custom test services](https://www.itb.ec.europa.eu/docs/services/latest/) are **enabled** but without requiring valid **API keys** to be provided. Such callbacks are made during test sessions to:
 
 - Notify the test engine to complete pending `receive` steps (or handler-enabled `interact` steps).
 - Send messages to add to the **test session log**.

gitb-ui/conf/health/testServiceCallbacks/ok_disabled.md

@@ -1,4 +1,4 @@
-Callbacks from custom test services are **disabled**. Such callbacks would be made during test sessions to:
+Callbacks from [custom test services](https://www.itb.ec.europa.eu/docs/services/latest/) are **disabled**. Such callbacks would be made during test sessions to:
 
 - Notify the test engine to complete pending `receive` steps (or handler-enabled `interact` steps).
 - Send messages to add to the **test session log**.

gitb-ui/conf/health/testServiceCallbacks/ok_enabled.md

@@ -1,4 +1,4 @@
-Callbacks from custom test services are **enabled** and require valid **API keys** to be presented. Such callbacks are made during test sessions to:
+Callbacks from [custom test services](https://www.itb.ec.europa.eu/docs/services/latest/) are **enabled** and require valid **API keys** to be presented. Such callbacks are made during test sessions to:
 
 - Notify the test engine to complete pending `receive` steps (or handler-enabled `interact` steps).
 - Send messages to add to the **test session log**.

gitb-ui/conf/health/testServiceCallbacks/warning.md

@@ -1,4 +1,4 @@
-Callbacks from custom test services are **enabled** but without requiring valid **API keys** to be provided. Such callbacks are made during test sessions to:
+Callbacks from [custom test services](https://www.itb.ec.europa.eu/docs/services/latest/) are **enabled** but without requiring valid **API keys** to be provided. Such callbacks are made during test sessions to:
 
 - Notify the test engine to complete pending `receive` steps (or handler-enabled `interact` steps).
 - Send messages to add to the **test session log**.