[7.14](backport #33318)[DOCS] Fix hard-coded documentation link (#33318)

[lcawl]

Backports #33318

This PR fixes the following hard-coded link, which will fail when we move away from "master" URLs:

17:07:03 INFO:build_docs: /tmp/docsbuild/target_repo/html/en/beats/devguide/8.5/creating-metricbeat-module.html contains broken links to:
17:07:03 INFO:build_docs: - en/beats/metricbeat/master/metricbeat-module-mysql.html

(cherry picked from commit b8b87c3)

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💔 Build Failed

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• Start Time: 2022-11-07T19:50:44.612+0000

• Duration: 25 min 6 sec

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• Took 16 min 26 sec . View more details here
• Description: make check

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• Took 0 min 0 sec . View more details here
• Description: Error 'hudson.AbortException: script returned exit code 2'

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