[docs](doc): Markdown(add OpenSSF badge)

[RalphHightower]

Pull request type

Please check the type of change your PR introduces:

• New blog post
• Bugfix
• Jekyll change(s)
• Liquid change(s)
• Markdown change(s)
• YAML change(s)
• Build error(s)
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

Language

• awk
• C/C++/C#
• Ruby
• Python

Files added

• README.md

Files modified

Files deleted

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Other information