Fix bug #674: typo in documentation example for BiCGSTAB. They are now proper snippet files.
diff --git a/doc/snippets/compile_snippet.cpp.in b/doc/snippets/compile_snippet.cpp.in
index 894cd52..82ae891 100644
--- a/doc/snippets/compile_snippet.cpp.in
+++ b/doc/snippets/compile_snippet.cpp.in
@@ -1,4 +1,4 @@
-#include <Eigen/Dense>
+#include <Eigen/Eigen>
 #include <iostream>
 
 using namespace Eigen;