### What problem does this PR solve?

Add license statement.

### Type of change

- [x] Refactoring

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

### What problem does this PR solve?

### Type of change

- [x] Refactoring

### What problem does this PR solve?

#1514 

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

### What problem does this PR solve?

fix file preview in file management

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

* init README of deepdoc, add picture processer.

* add resume parsing