Update remark on ctc.root config variable in ctc function's docstring

theano/tensor/nnet/ctc.py

@@ -198,8 +198,9 @@ def ctc(activations, labels, input_lengths):
 
     Notes
     -----
-    Using the loss function requires that Baidu's warp-ctc library is installed and the
-    configuration variable `config.ctc.root` be properly set.
+    Using the loss function requires that Baidu's warp-ctc library is installed. If the
+    warp-ctc library is not on the compiler's default library path, the configuration
+    variable ``config.ctc.root`` be properly set.
 
     Parameters
     ----------