### What problem does this PR solve?

update docs for release 0.8.0

### Type of change

- [x] Documentation Update

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Co-authored-by: writinwaters <93570324+writinwaters@users.noreply.github.com>

### What problem does this PR solve?

#720 

### Type of change

- [x] Documentation Update

### What problem does this PR solve?

_Briefly describe what this PR aims to solve. Include background context
that will help reviewers understand the purpose of the PR._

### Type of change

- [x] Documentation Update

---------

Signed-off-by: Jin Hai <haijin.chn@gmail.com>

### What problem does this PR solve?

_Briefly describe what this PR aims to solve. Include background context
that will help reviewers understand the purpose of the PR._

### Type of change

- [x] Documentation Update

### What problem does this PR solve?

Added guide with instructions on managing files in RAGFlow. 

### Type of change

- [x] Documentation Update