Docs: Update version references to v0.20.0 in READMEs and docs (#9164)

### What problem does this PR solve?

- Update version tags in README files (including translations) from
v0.19.1 to v0.20.0
- Modify Docker image references and documentation to reflect new
version
- Update version badges and image descriptions
- Maintain consistency across all language variants of README files

### Type of change

- [x] Documentation Update

uv.lock

@@ -5188,7 +5188,7 @@ wheels = [
 
 [[package]]
 name = "ragflow"
-version = "0.19.1"
+version = "0.20.0"
 source = { virtual = "." }
 dependencies = [
     { name = "akshare" },