audio_core: Amend documentation tags

Resolves a wackload of -Wdocumentation warnings due to mismatching tags
and whatnot.

src/audio_core/audio_manager.h

@@ -76,7 +76,7 @@ public:
 
 private:
     /**
-     * Main thread, waiting on a manager signal and calling the registered fucntion.
+     * Main thread, waiting on a manager signal and calling the registered function.
      */
     void ThreadFunc();