Fix broken docs-lint markdown job

What does this MR do and why?

This MR fixes a broken docs-lint markdown job:

The error was MD012/no-multiple-blanks (Multiple consecutive blank lines [Expected: 1; Actual: 2]).

$ markdownlint --config .markdownlint.yml --config .markdownlint.yml doc --rules doc/.markdownlint/rules
doc/development/identity_verification.md:17 MD012/no-multiple-blanks Multiple consecutive blank lines [Expected: 1; Actual: 2]
error Command failed with exit code 1.

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