Set metric on createIndex

[julioxavierr]

Problem

Describe the purpose of this change. What problem is being solved and why?

Resolves #6

Solution

Describe the approach you took. Link to any relevant bugs, issues, docs, or other resources.

Included the metric parameter to the createIndex call.

Type of Change

• 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 not work as expected)
• This change requires a documentation update
• Infrastructure change (CI configs, etc)
• Non-code change (docs, etc)
• None of the above: (explain here)

Test Plan

Describe specific steps for validating this change.

• Follow the instructions in README. The index creation should fail.

[dhurlburtusa]

It would be great to get this merged so that potential customers don't shy away from broken examples.