Fix documentation bug about threading

doc/threading.dox

@@ -6,16 +6,16 @@ libssh may be used in multithreaded applications, but under several conditions :
  - Threading must be initialized during the initialization of libssh. This 
    initialization must be done outside of any threading context.
  - If pthreads is being used by your application (or your framework's backend),
-   you must link with libssh_threads_pthread dynamic library and initialize 
+   you must link with libssh_threads dynamic library and initialize 
    threading with the ssh_threads_pthreads threading object.
  - If an other threading library is being used by your application, you must 
    implement all the methods of the ssh_threads_callbacks_struct structure
    and initialize libssh with it.
  - At all times, you may use different sessions inside threads, make parallel
-   connections, read/write on different sessions and so on. You can use a
-   single session in several channels at the same time. This will lead to
-   internal state corruption. This limitation is being worked out and will
-   maybe disappear later.
+   connections, read/write on different sessions and so on. You *cannot* use a
+   single session (or channels for a single session) in several threads at the same 
+   time. This will most likely lead to internal state corruption. This limitation is
+   being worked out and will maybe disappear later.
    
 @subsection threads_init Initialization of threads
 
@@ -44,10 +44,10 @@ ssh_threads_set_callbacks(ssh_threads_pthread);
 ssh_init();
 @endcode
 
-However, you must be sure to link with the library ssh_threads_pthread. If 
+However, you must be sure to link with the library ssh_threads. If 
 you're using gcc, you must use the commandline
 @code
-gcc -o output input.c -lssh -lssh_threads_pthread
+gcc -o output input.c -lssh -lssh_threads
 @endcode