chore(readme): Optimize the text description in README

[pkudba]

Description

Checklist

Please feel free to remove inapplicable items for your PR.

• The PR title starts with [$CATEGORY] (such as [Docs], [Fix], [Feature], [Refactor])
• Related issue is referred in this PR
• The markdown and latex are rendered correctly.
• The code in PR is well-documented.
• The PR is complete and small, read the Google eng practice (CL equals to PR) to understand more about small PR.

[keli-wen]

it seems fail with the following message:

trim trailing whitespace.................................................Failed
- hook id: trailing-whitespace
- exit code: 1
- files were modified by this hook

I recommend @pkudba to execute the following commands:

pip install pre-commit
pre-commit install
pre-commit run --all-files

to automatically format the markdown file in local env.

[keli-wen]

After polish and pass the pre-check, you can re-request my review. After the approval, we can merge the change into our master branch.

[pkudba]

All pre-checks have already been passed.

[keli-wen]

LGTM