ntdll: Document RtlSetThreadErrorMode and RtlGetThreadErrorMode.

dlls/ntdll/rtl.c

@@ -1168,6 +1168,16 @@ NTSTATUS WINAPI RtlDecompressBuffer(USHORT CompressionFormat, PUCHAR Uncompresse
 
 /***********************************************************************
  *  RtlSetThreadErrorMode 	[NTDLL.@]
+ *
+ * Set the thread local error mode.
+ *
+ * PARAMS
+ *  mode    [I] The new error mode
+ *  oldmode [O] Destination of the old error mode (may be NULL)
+ *
+ * RETURNS
+ *  Success: STATUS_SUCCESS
+ *  Failure: STATUS_INVALID_PARAMETER_1
  */
 NTSTATUS WINAPI RtlSetThreadErrorMode( DWORD mode, LPDWORD oldmode )
 {
@@ -1183,6 +1193,14 @@ NTSTATUS WINAPI RtlSetThreadErrorMode( DWORD mode, LPDWORD oldmode )
 
 /***********************************************************************
  *  RtlGetThreadErrorMode 	[NTDLL.@]
+ *
+ * Get the thread local error mode.
+ *
+ * PARAMS
+ *  None.
+ *
+ * RETURNS
+ *  The current thread local error mode.
  */
 DWORD WINAPI RtlGetThreadErrorMode( void )
 {