Fix Snowplow Micro broken link in Data for Product Managers page

Why is this change being made?

This MR fixes a broken link in Data for Product Managers page.

Broken link

https://snowplowlegacy.com/blog/2019/07/17/introducing-snowplow-micro/

Correct link

https://snowplow.io/blog/introducing-snowplow-micro/

This link is taken for another Gitalb page: https://docs.gitlab.cn/14.0/ee/development/snowplow/index.html#snowplow-micro

Author Checklist

• Provided a concise title for this Merge Request (MR)
• Added a description to this MR explaining the reasons for the proposed change, per say why, not just what
  • Copy/paste the Slack conversation to document it for later, or upload screenshots. Verify that no confidential data is added, and the content is SAFE
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  • If the DRI for the page/s being updated isn’t immediately clear, then assign it to one of the people listed in the Maintained by section on the page being edited
  • If your manager does not have merge rights, please ask someone to merge it AFTER it has been approved by your manager in #mr-buddies
  • The when to get approval handbook section explains the workflow in more detail
• If the changes affect team members, or warrant an announcement in another way, please consider posting an update in #whats-happening-at-gitlab linking to this MR
  • If this is a change that directly impacts the majority of global team members, it should be a candidate for #company-fyi. Please work with internal communications and check the handbook for examples.

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