Escape pipe character when generating Markdown

[khos2ow]

Prerequisites

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• This pull request fixes a bug.
• This pull request adds a feature.
• This pull request enhances existing functionality.
• This pull request introduces breaking change.

For more information, see the Contributing Guide.

Description

This PR esacpes pipe (|) while generating Markdown document or table.

Issues Resolved

List any existing issues this pull request resolves. #112

Checklist

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• I have read the Contributing Guidelines.

Tests

• I have added tests to cover my changes.
• All tests pass when I run make test.

Documentation

• My change requires a change to the documentation.
• I have updated the documentation accordingly.

Code Style

• My code follows the code style of this project.

[metmajer]

Great stuff, @khos2ow and thanks for taking the initiative!