Add detection for zsh completion files

[griano]

Chenges

• In ZSH completions files start with #compdef and #autoload, like these files
• I also added detection for some typical ZSH env files.

Testing

• rake passes all tests
• Example with #autoload

$ ./bin/rougify guess =(curl -sq https://github.com/zsh-users/zsh/blob/master/Completion/Base/Utility/_arguments)
{ tag: "html", title: "HTML", desc: "HTML, the markup language of the web" }

• Example with #compdef

$ ./bin/rougify guess =(curl -sq https://github.com/zsh-users/zsh/blob/master/Completion/Zsh/Command/_alias)                                                                               
{ tag: "html", title: "HTML", desc: "HTML, the markup language of the web" }

[tancnle]

Thank you for your contribution @griano ❤️ I have a small suggestion for your consideration.

Additionally, would it be possible if you can add some tests for the new guessing logic? You can find some existing examples here. Let me know if you need any assistance.

[tancnle]

Thank you for considering the suggestions, @griano. The change LGTM 🚀

[griano]

Addressed the requested changes.

Testing:

The test above were reported incorrectly. In these tests I use the raw URL to download the actual file.

Test with #autoload

$ bin/rougify guess <(curl -sq https://raw.githubusercontent.com/zsh-users/zsh/master/Completion/Base/Utility/_arguments) 
{ tag: "shell", title: "shell", desc: "Various shell languages, including sh and bash" }

Test with `#compdef``

$ bin/rougify guess <(curl -qs https://raw.githubusercontent.com/zsh-users/zsh/master/Completion/Zsh/Command/_alias)
{ tag: "shell", title: "shell", desc: "Various shell languages, including sh and bash" }
```bash