Category name in adoc files should be case insensitive

[gvenzl]

When the category name in an adoc feature file is uppercase, it breaks the build, resulting in:

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[13:04:41.871] ERROR (asciidoctor): target of xref not found: categories:SQL/index.adoc
    file: /Users/gvenzl/git/oracle-sql-features.github.io/docs/modules/categories/pages/sql/features/wide-tables.adoc
    source: /Users/gvenzl/git/oracle-sql-features.github.io (branch: remove-how-to <worktree> | start path: docs)
[13:04:42.149] ERROR (asciidoctor): target of xref not found: categories:SQL/index.adoc
    file: /Users/gvenzl/git/oracle-sql-features.github.io/docs/modules/categories/pages/sql/23.2/wide-tables.adoc
    source: /Users/gvenzl/git/oracle-sql-features.github.io (branch: remove-how-to <worktree> | start path: docs)
[13:04:42.539] ERROR (asciidoctor): target of xref not found: categories:SQL/index.adoc
    file: /Users/gvenzl/git/oracle-sql-features.github.io/docs/modules/versions/pages/23.2/sql/wide-tables.adoc
    source: /Users/gvenzl/git/oracle-sql-features.github.io (branch: remove-how-to <worktree> | start path: docs)
[13:04:42.889] ERROR (asciidoctor): target of xref not found: categories:SQL/index.adoc
    file: /Users/gvenzl/git/oracle-sql-features.github.io/docs/modules/versions/pages/23.2/features/wide-tables.adoc
    source: /Users/gvenzl/git/oracle-sql-features.github.io (branch: remove-how-to <worktree> | start path: docs)
[13:04:42.969] ERROR (asciidoctor): target of xref not found: SQL/index.adoc
    file: /Users/gvenzl/git/oracle-sql-features.github.io/docs/modules/categories/nav.adoc
    source: /Users/gvenzl/git/oracle-sql-features.github.io (branch: remove-how-to <worktree> | start path: docs)
[13:04:42.971] ERROR (asciidoctor): target of xref not found: SQL/features/wide-tables.adoc
    file: /Users/gvenzl/git/oracle-sql-features.github.io/docs/modules/categories/nav.adoc
    source: /Users/gvenzl/git/oracle-sql-features.github.io (branch: remove-how-to <worktree> | start path: docs)
[13:04:42.972] ERROR (asciidoctor): target of xref not found: SQL/23.2/index.adoc
    file: /Users/gvenzl/git/oracle-sql-features.github.io/docs/modules/categories/nav.adoc
    source: /Users/gvenzl/git/oracle-sql-features.github.io (branch: remove-how-to <worktree> | start path: docs)
[13:04:42.973] ERROR (asciidoctor): target of xref not found: SQL/23.2/wide-tables.adoc
    file: /Users/gvenzl/git/oracle-sql-features.github.io/docs/modules/categories/nav.adoc
    source: /Users/gvenzl/git/oracle-sql-features.github.io (branch: remove-how-to <worktree> | start path: docs)
[13:04:43.005] ERROR (asciidoctor): target of xref not found: 23.2/SQL/index.adoc
    file: /Users/gvenzl/git/oracle-sql-features.github.io/docs/modules/versions/nav.adoc
    source: /Users/gvenzl/git/oracle-sql-features.github.io (branch: remove-how-to <worktree> | start path: docs)
[13:04:43.006] ERROR (asciidoctor): target of xref not found: 23.2/SQL/wide-tables.adoc
    file: /Users/gvenzl/git/oracle-sql-features.github.io/docs/modules/versions/nav.adoc
    source: /Users/gvenzl/git/oracle-sql-features.github.io (branch: remove-how-to <worktree> | start path: docs)
Site generation complete!
Open file:///Users/gvenzl/git/oracle-sql-features.github.io/build/site/index.html in a browser to view your site.
gvenzl@gvenzl-mac oracle-sql-features.github.io %

And subsequently:

The category name ideally should be treated case insensitive.