Fixing the bug caused by changed tsdb api, updating the docs

[WenjieDu]

What does this PR do?

1. fixing TSDB has adjusted its API in v0.1 #165;
2. updating the docs;

Before submitting

• This PR is made to fix a typo or improve the docs (you can dismiss the other checks if this is the case).
• Was this discussed/approved via a GitHub issue? Please add a link to it if that's the case.
• I have commented my code, particularly in hard-to-understand areas.
• I have written necessary tests and already run them locally.

[coveralls]

Pull Request Test Coverage Report for Build 5811549790

• 5 of 6 (83.33%) changed or added relevant lines in 3 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.03%) to 84.189%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pypots/utils/metrics.py	3	4	75.0%

Files with Coverage Reduction	New Missed Lines	%
pypots/clustering/crli/model.py	2	93.71%

Totals
Change from base Build 5614932710:	0.03%
Covered Lines:	3099
Relevant Lines:	3681

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💛 - Coveralls