README.md: add link to sonarcloud

README.md

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 I did this fork to fix blocking error - so it is the only fork of Geeknote that WORKS, on Python 3. Looks like nobody else is interested in Geeknote anymore, so I declare this repo as main. Feel free to contribute.
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+[![Code Smells](https://sonarcloud.io/api/project_badges/measure?project=vitaly-zdanevich_geeknote&metric=code_smells)](https://sonarcloud.io/summary/new_code?id=vitaly-zdanevich_geeknote)
+
 Geeknote for Evernote (or 印象笔记)
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