bug(docs) correct typo in installation.md

[mikefidel]

Spelling error in file docs/usage/installation.md.

Description

Change single occurrence of text "unkpg's" to "unpkg's" (quotes omitted)

Motivation and Context

Trivial document change and my first ever PR. Hoping to contribute more substantially in the future.

How Has This Been Tested?

No testing.

Screenshots (if appropriate):

n/a

Types of changes

• No code changes (changes to documentation, CI, metadata, etc)
• Dependency changes (any modification to dependencies in package.json)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[shockey]

Thanks @mikefidel 😄