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extensibility is probably the right word?

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Update README.md for GitBucket 3.8 release

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Update description about support

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(refs #867)Providing checksum has started since 3.7

GitBucket 3.7.0 release

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Fix typo in README.md

reference gitbucket-h2-backup-plugin in README

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GitBucket 3.5.0 release

GitBucket 3.4 release

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Add IntelliJ IDEA logo

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