docs: fix typos in CONTRIBUTING.md

[ajitzero]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/ng-primitives/ng-primitives/blob/main/CONTRIBUTING.md#-commit-message-guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation changes
• Other... Please describe:

Issue

Closes #

What does this PR implement/fix?

Fixes some typos in CONTRIBUTING.MD:

• out -> our
• troubleshoting -> troubleshooting
• availble -> available

Does this PR introduce a breaking change?

• Yes
• No

[ashley-hunter]

Thank you very much! Documentation has never been my strong point 😅 appreciate the improvements!

[ajitzero]

Documentation has never been my strong point

You're too humble 🙌 This is one of the best contributing guides out there, and I was checking it again today to use it as a template for another project. This is great!

[ashley-hunter]

Thank you 🙏 well you've just made it even better, so thank you!