Added story grouping functionality

• Basic story grouping functionality in sidebar
• Update to .NET 8

Fixes

• Updated setup instruction with missing steps
• Fixed UI styling

Initial beta release with nuget package

What's Changed

• Update to .net6.0 by @TheDayIsMyEnemy in #1
• Added nuspec by @aeagle in #3

New Contributors

• @TheDayIsMyEnemy made their first contribution in #1
• @aeagle made their first contribution in #3

Full Changelog: https://github.com/aeagle/blazor-book/commits/0.0.1-beta.1