Feat/doc (#188)

* add logo picture and chagne jzfs joint management picture

* change logo file name of dark mode

* change size of picture

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Author: taoshengshi

README.md

@@ -58,7 +58,7 @@
 
 JZFS adapts principles of open-source software development and distribution to address the technical challenges of data management, data sharing, and digital provenance collection across the life cycle of digital objects.
 
-<img src="./docs/jzfs-joint-management.png" width="400">
+<div style="text-align: center"><img src="./docs/jzfs-joint-management.png" width="400" /></div>
 
 Compared with code in software development, data tend not to be as precisely
 identified because data versioning is rarely or only coarsely practiced. Scientific computation