Improve sidebar navigation category titles

[bhouston]

Improve Sidebar Navigation Category Titles

This PR addresses issue #34 by adding _category_.json files to customize the display names of sidebar categories.

Changes Made

• Added _category_.json to the getting-started directory with a proper "Getting Started" label
• Added _category_.json to the usage directory with a proper "Usage Guide" label
• Set appropriate positions and added descriptive text for each category

Before / After

Before:

• Categories displayed as lowercase, hyphenated directory names: "getting-started" and "usage"

After:

• Categories now display as proper titles: "Getting Started" and "Usage Guide"

Testing Done

• Built the site locally and verified that the sidebar displays the correct category names
• Ensured navigation structure remains intact

This simple approach maintains the existing directory structure while providing a more professional appearance in the navigation.

[bhouston]

Superseded by PR #36 which provides an improved solution that eliminates duplicate entries