Remove Chinese documentation link and center align image in README

Removed a Chinese documentation link and centered the image in the README file.

Bump version to 1.0.7 in Cargo files

Update the package version from 1.0.6 to 1.0.7 in both Cargo.toml and Cargo.lock files, maintaining consistency across the project.

Update features: Batch Conversion, File Processing, Custom Rules.

- Added support for batch variable name conversion.
- Implemented batch conversion of variable names in files.
- Enabled users to define custom conversion rules.