Update 10_asynchronous_custom_input.cpp (#1696)

Fix typo "funtion" -> "function" on line 40

examples/tutorial_api_cpp/10_asynchronous_custom_input.cpp

@@ -37,7 +37,7 @@ public:
         if (mClosed || mImageFiles.size() <= mCounter)
         {
             op::opLog("Last frame read and added to queue. Closing program after it is processed.", op::Priority::High);
-            // This funtion stops this worker, which will eventually stop the whole thread system once all the frames
+            // This function stops this worker, which will eventually stop the whole thread system once all the frames
             // have been processed
             mClosed = true;
             return nullptr;