docs: add snipsync lines to envconfig samples

Author: lennessyy

core/src/main/java/io/temporal/samples/envconfig/LoadFromFile.java

@@ -1,5 +1,5 @@
 package io.temporal.samples.envconfig;
-
+/** @@@SNIPSTART java-env-config-profile */
 import io.temporal.client.WorkflowClient;
 import io.temporal.client.WorkflowClientOptions;
 import io.temporal.envconfig.ClientConfigProfile;
@@ -77,3 +77,4 @@ public static void main(String[] args) {
     }
   }
 }
+/** @@@SNIPEND */

core/src/main/java/io/temporal/samples/envconfig/LoadProfile.java

@@ -1,5 +1,5 @@
 package io.temporal.samples.envconfig;
-
+/** @@@SNIPSTART java-env-config-profile-with-overrides */
 import io.temporal.client.WorkflowClient;
 import io.temporal.client.WorkflowClientOptions;
 import io.temporal.envconfig.ClientConfigProfile;
@@ -85,3 +85,4 @@ public static void main(String[] args) {
     }
   }
 }
+/** @@@SNIPEND */