Fix docs generation flow for Pester 6 and regenerate 6.0.0-rc2 docs

[nohwnd]

Why

The Update Pester Docs workflow broke when regenerating docs for 6.0.0-rc2:

Unable to find type [PesterConfiguration]

Root cause: Pester 6 ships a .NET 8 assembly and requires PowerShell 7.4+, but the workflow deliberately downgraded to 7.3 (to dodge platyPS #663). On 7.3 the net8.0 Pester.dll can't load, so [PesterConfiguration] never registers and generation fails. The two workarounds were mutually exclusive.

Regenerating on 7.4+ then surfaced two further issues that broke the Docusaurus (MDX 3) build, both fixed here.

What

• generate-pester-docs.yml — drop the PowerShell 7.3 downgrade step; run on the runner's default 7.4+.
• generate-command-reference.ps1 — post-process the generated MDX to:
  • strip the spurious ProgressAction common parameter (SYNTAX blocks + ### -ProgressAction sections) that platyPS emits on 7.4+ (#663);
  • keep the [<CommonParameters>] SYNTAX token and the ### CommonParameters section as platyPS produces them. Because ProgressAction is longer than [<CommonParameters>] and always sits right before it, removing ProgressAction could orphan [<CommonParameters>] on a dangling wrapped line. Format-SyntaxCommonParameters re-wraps it onto its own line only when the SYNTAX line would exceed platyPS's wrap width (~110 chars), reproducing the layout platyPS emits natively without ProgressAction (no dangling lines, no horizontal scroll);
  • repair mismatched example code fences (Repair-ExampleFences). rc2's comment-based help embeds Markdown code fences (and a powereshell typo) inside .EXAMPLE; platyPS double-wraps them into mismatched fences, so MDX 3 mispaired them and tried to parse an example's @{ ... } as a JSX expression → Could not parse expression with acorn. The pass normalizes each example into a single well-formed ```powershell block.
• generate-pesterconfiguration-docs.ps1 — replace the machine-specific Run.RepoRoot default (eagerly resolved to the generator's git root) with an illustrative C:\MyProject placeholder so no build path leaks into the published docs. (Kept main's MDX-escaping + null-safety from Update v6 docs from 6.0.0 release notes #379/Claim PowerShell 7.4+ support instead of 7.2+ #381.)
• docs/usage/configuration.mdx — preamble Run.Path examples use C:\MyProject\tests; Run.RepoRoot renders as 'C:\MyProject'.
• Regenerated the command reference + Configuration page for 6.0.0-rc2: adds Should-BeHashtable and the new rc2 config options (Run.Parallel, Run.BeforeContainer, Run.ParallelThrottleLimit, Run.RepoRoot, CodeCoverage.ReportRoot, Debug.ShowStartMarkers).

This branch also merges current main (PRs #379–#383, incl. the MDX-escaping config-generator changes and new usage pages).

Verification

• Regenerated locally on PowerShell 7.5.5 with Pester 6.0.0-rc2: 0 ProgressAction across all command files; [<CommonParameters>] token + ### CommonParameters section present in all 65 command pages; longest SYNTAX line is 110 chars (no horizontal scroll); no machine-path leaks.
• yarn build passes locally and the Netlify deploy preview is green — the rc2 MDX compiles.
• Re-dispatched the Update Pester Docs workflow against this branch: succeeds on CI (PS 7.4+) and opens no docs-update PR, confirming the committed docs exactly match what the scripts generate (idempotent, no drift).