Fix build-dev-docs and update docs

[gonzaloriestra]

WHY are these changes introduced?

The build-dev-docs command is failing unless you have pnpx manually installed, because is not included by default in pnpm anymore

WHAT is this pull request doing?

• Use pnpm to make the command work for everyone
• Update docs

Checklist

• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've considered possible documentation changes
• I've considered analytics changes to measure impact
• The change is user-facing — I've identified the correct bump type (patch for bug fixes · minor for new features · major for breaking changes) and added a changeset with pnpm changeset add

[gonzaloriestra]

Merge activity

• May 11, 11:21 AM UTC: A user started a stack merge that includes this pull request via Graphite.
• May 11, 11:21 AM UTC: @gonzaloriestra added this pull request to the GitHub merge queue with Graphite.