Fix "section title out of sequence: expected level" warnings
    
    Fixes:
    ```
    [14:58:39.162] WARN (asciidoctor): section title out of sequence: expected level 2, got level 3
        file: /antora/docs/modules/ROOT/pages/virtualization-install.adoc:134
        source: /antora (refname: main <worktree>, start path: docs)
    [14:58:39.274] WARN (asciidoctor): section title out of sequence: expected level 1, got level 2
        file: /antora/wg/modules/ROOT/pages/wg-communicating.adoc:17
        source: /antora (refname: main <worktree>, start path: wg)
    [14:58:39.322] WARN (asciidoctor): section title out of sequence: expected level 3, got level 4
        file: /antora/wg/modules/ROOT/pages/docs/product-requirements-document.adoc:83
        source: /antora (refname: main <worktree>, start path: wg)
    [14:58:39.323] WARN (asciidoctor): section title out of sequence: expected level 3, got level 4
        file: /antora/wg/modules/ROOT/pages/docs/product-requirements-document.adoc:89
        source: /antora (refname: main <worktree>, start path: wg)
    [14:58:39.326] WARN (asciidoctor): section title out of sequence: expected level 3, got level 4
        file: /antora/wg/modules/ROOT/pages/docs/product-requirements-document.adoc:95
        source: /antora (refname: main <worktree>, start path: wg)
    [14:58:39.327] WARN (asciidoctor): section title out of sequence: expected level 3, got level 4
        file: /antora/wg/modules/ROOT/pages/docs/product-requirements-document.adoc:102
        source: /antora (refname: main <worktree>, start path: wg)
    ```