什么是一个好的VCS存储库来阅读/帮助？

I've been writing code, mostly proprietary, for a long time; spaghetti code and the like. I took a few years out of the industry though and feel like I missed something enormous. I've spent some time studying books but I want to get my hands a little dirty - so I ask, what would be a good VCS repository to read/involve myself with?I've been writing code, mostly proprietary, for