Add note about soft deprecation for service checks (#19804)

Author: iliakur

datadog_checks_base/datadog_checks/base/checks/base.py

@@ -955,6 +955,10 @@ def service_check(self, name, status, tags=None, hostname=None, message=None, ra
         # type: (str, ServiceCheckStatus, Sequence[str], str, str, bool) -> None
         """Send the status of a service.
 
+        !!! warning "Soft Deprecation"
+            When building new checks avoid submitting service checks.
+            **Checks that already submit service checks will continue to do so.**
+
         Parameters:
             name (str):
                 the name of the service check