Backport of Fixed broken link in the ECS documentation into release/1.18.x

[hc-github-team-consul-core]

Backport

This PR is auto-generated from #21018 to be assessed for backporting due to the inclusion of the label backport/1.18.

The below text is copied from the body of the original PR.

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Description

Fixing broken links in the ECS documentation

PR Checklist

• [ ] updated test coverage
• [x] external facing docs updated
• [ ] appropriate backport labels added
• [x] not a security concern

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Overview of commits

• 064f5bafbf1e5cdb7b1901ca95a6651b874dbac8