cwThreadMach.h : Add comments.

cwThreadMach.h

@@ -8,11 +8,23 @@ namespace cw
     typedef handle<struct thread_mach_str> handle_t;
     typedef thread::cbFunc_t               threadFunc_t;
 
+    // Create a thread machine instance.
+    // contextArray[ threadN ][ contextRecdByteN ] is an optional  blob consisting of 'threadN' records each of size 'contextRecdByteN'.
+    // Each of the records then becomes the entity which is used as the 'arg' value in the callback for the first 'threadN' threads.
     rc_t create(  handle_t& hRef, threadFunc_t threadFunc=nullptr, void* contextArray=nullptr, unsigned contexRecdByteN=0, unsigned threadN=0 );
     rc_t destroy( handle_t& hRef );
+
+    // Create an additional thread. Note that the additional thread will be started by the next
+    // call to 'start()'.
     rc_t add(   handle_t h, threadFunc_t threadFunc, void* arg );
+
+    // Start all threads    
     rc_t start( handle_t h );
+    
+    // Stop all threads.
     rc_t stop(  handle_t h );
+
+    // Check if all threads are shutdown.
     bool is_shutdown( handle_t h );
   }
 }