Fix typo

Author: huydhn

examples/demo-apps/android/LlamaDemo/app/src/androidTest/java/com/example/executorchllamademo/PerfTest.java

@@ -37,7 +37,7 @@ public void testTokensPerSecond() {
         // Check that the model can be load successfully
         assertEquals(0, loadResult);
 
-        // Run some testing prompt
+        // Run a testing prompt
         mModule.generate("How do you do! I'm testing llama2 on mobile device", PerfTest.this);
         assertFalse(tokensPerSecond.isEmpty());