a small mistake in doc

[Xiaokeai18]

In the tutorial doc of chapter 1 "Basics/variables", there might be a misktake here:

# "variable_list_custom" is the list of variables that we want to initialize.
variable_list_custom = [weights, custom_variable]

# The initializer
init_custom_op = tf.variables_initializer(var_list=all_variables_list)

The last line of the code above might end up with var_list=variable_list_custom, not all_variables_list.

Here's url of the doc:
https://github.com/astorfi/TensorFlow-World/tree/master/docs/tutorials/1-basics/variables#initializing-specific-variables
Thank you for your repo, it helps me a lot.