Update config.ctc.root flag description in config doc

Signed-off-by: João Victor Tozatti Risso <joaovictor.risso@gmail.com>

Update config.ctc.root flag description in config doc
2715fdfb · João Victor Tozatti Risso · 6e5efd7b · 2715fdfb
--- a/doc/library/config.txt
+++ b/doc/library/config.txt
@@ -757,7 +757,9 @@ import theano and print the config variable, as in:
    Default: ``''``
-    Location of the warp-ctc library.
+    Location of the warp-ctc folder. The folder should contain a build
+    subfolder with the shared library (libwarpctc.so), and another
+    subfolder called include, with the CTC library header.
 .. attribute:: config.gcc.cxxflags