Fix doxygen command. (No review. Trivial.)

git-svn-id: svn://bind10.isc.org/svn/bind10/trunk@3545 e5f2f494-b856-4b98-b285-d166d9295462

src/lib/exceptions/exceptions.h

@@ -40,7 +40,7 @@ public:
     /// file line number.
     ///
     /// @param file the file name where the exception was thrown.
-    /// @param line the line in @ref file where the exception was thrown.
+    /// @param line the line in \a file where the exception was thrown.
     /// @param what a description (type) of the exception.
     Exception(const char* file, size_t line, const char* what) :
         file_(file), line_(line), what_(what) {}