Add Phel language

[JesusValeraDev]

📚 Description

There are more than 370 files in Github using the .phel extension.

Some remarkable projects:

• https://phel-lang.org/documentation/in-the-wild/#projects

Plugins for different applications

• IntelliJ IDEA: https://github.com/phel-lang/phel-intellij-plugin → Marketplace
• VS Code: https://github.com/phel-lang/phel-vs-code-extension
• Vim: https://github.com/danirod/phel.vim
• Emacs: https://codeberg.org/mmontone/interactive-lang-tools

📓 Checklist:

• [x] I am adding a new language.
  • [x] The extension of the new language is used in hundreds of repositories on GitHub.com.
    • Search results for each extension:
      • https://github.com/search?q=path%3A*.phel&type=code
  • [x] I have included a real-world usage sample for all extensions added in this PR:
    • https://github.com/JesusValera/linguist/blob/add-phel-language/samples/Phel/sample.phel
    • Sample license(s):
  • [ ] I have included a syntax highlighting grammar.
  • [ ] I have updated the heuristics to distinguish my language from others using the same extension.

The last two points are not selected because they use a Common Lisp grammar & the extension is unique (.phel).

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Please let me know if something is missing. I'd be glad to keep improving the PR if necessary! 🤞🏼