Adding Codety into the cppcheck-htdocs index tool list

[random1223]

Add Codety into the tool list as Codety Scanner uses cppcheck as C&C++ code analyzer, Codety Scanner provides out-of-box cppcheck integration for automating the code reviews.
Here're some examples of Codety Scanner's github integration:

• GitHub pull request comments (Demo codetyio/codety-scanner#15 (comment))
• GitHub pull request review comments (check example here)
• GitHub check run annotations (check example here)

Codety also added cppcheck into the credits list: https://github.com/codetyio/codety-scanner/blob/main/CREDITS.md

This is Codety Scanner's git repo: https://github.com/codetyio/codety-scanner