feat: normalize consecutive newlines in markdown descriptions to pres…

[Kim-Yukyung]

Related Issue

Fixes #531

Description

This PR addresses a formatting issue where multi-paragraph markdown descriptions inside attribute list items were breaking the surrounding list structure.

In Markdown, two or more consecutive newline characters (\n\n) terminate a list item and start a new paragraph outside the list. This caused multi-line attribute descriptions to appear misaligned or outside of their list items.

To resolve this, the PR introduces a normalization step that collapses multiple consecutive newlines into a hard line break (" \n"). This approach preserves visual line separation while maintaining list integrity across nested and top-level attributes.

The normalization is applied in both WriteAttributeDescription and WriteNestedAttributeTypeDescription to ensure consistent behavior across all schema paths.

Rollback Plan

• [x] If a change needs to be reverted, we will roll out an update to the code within 7 days.

Changes to Security Controls

Are there any changes to security controls (access controls, encryption, logging) in this pull request? If so, explain.

N/A

This PR only modifies Markdown formatting logic in documentation generation.

[hashicorp-cla-app[bot]]

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