Fix minor typo

Author: larrytin

tensorflow/docs_src/programmers_guide/graphs.md

@@ -89,7 +89,7 @@ to all API functions in the same context.  For example:
 * Executing `v = tf.Variable(0)` adds to the graph a @{tf.Operation} that will
   store a writeable tensor value that persists between @{tf.Session.run} calls.
   The @{tf.Variable} object wraps this operation, and can be used [like a
-  tensor](#tensor-like-objects), which will read the current value of the
+  tensor](#tensor-like_objects), which will read the current value of the
   stored value. The @{tf.Variable} object also has methods such as
   @{tf.Variable.assign$`assign`} and @{tf.Variable.assign_add$`assign_add`} that
   create @{tf.Operation} objects that, when executed, update the stored value.