docs: improve documentation

[tutkli]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our
  guidelines: https://github.com/tutkli/ngx-sonner/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 content changes
• Other... Please describe:

What is the current behavior?

Closes #

What is the new behavior?

• Docs comments have been added to types.
• README file has been updated with more info

Does this PR introduce a breaking change?

• Yes
• No

Other information

[tutkli]

🎉 This PR is included in version 1.0.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀