update tutorial dict part to reflect dict is ordered

BPO	32673
Nosy	@vadmium, @zhangyangyu, @chason
Superseder	bpo-32337: Dict order is now guaranteed, so add tests and doc for it

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2018-01-26.07:39:38.399>
created_at = <Date 2018-01-26.06:10:52.269>
labels = ['3.7', 'docs']
title = 'update tutorial dict part to reflect dict is ordered'
updated_at = <Date 2018-01-26.07:39:38.397>
user = 'https://github.com/zhangyangyu'

bugs.python.org fields:

activity = <Date 2018-01-26.07:39:38.397>
actor = 'xiang.zhang'
assignee = 'docs@python'
closed = True
closed_date = <Date 2018-01-26.07:39:38.399>
closer = 'xiang.zhang'
components = ['Documentation']
creation = <Date 2018-01-26.06:10:52.269>
creator = 'xiang.zhang'
dependencies = []
files = []
hgrepos = []
issue_num = 32673
keywords = []
message_count = 3.0
messages = ['310737', '310744', '310747']
nosy_count = 4.0
nosy_names = ['docs@python', 'martin.panter', 'xiang.zhang', 'chason.chaffin']
pr_nums = []
priority = 'normal'
resolution = 'duplicate'
stage = 'resolved'
status = 'closed'
superseder = '32337'
type = None
url = 'https://bugs.python.org/issue32673'
versions = ['Python 3.7']