feat: add missing jig convert information

[tuxmea]

Short description

Jig is now able to convert PDK based modules to VoxBox compatibility.
e.g. PDK used the puppetlabs_spec_helper gem, which has been removed from OpenVoxtesting.

Checklist

I have:

• read the CONTRIBUTING.md document
• read and accepted the Developer Certificate of Origin document and added a Signed-off-by annotation to each of my commits
• read and accepted the AI Policy document and added Generated-by or Assisted-by annotations to each of my commits created with the help of an AI agent
• tested this code
• included documentation (including possible behaviour changes)
• documented the code
• added or modified regression test(s)
• added or modified unit test(s)

[Copilot]

Pull request overview

Updates the DevKit migration guide to document Jig’s new ability to convert PDK-based modules for OpenVox/VoxBox compatibility, helping users transition off the PDK with less manual editing.

Changes:

• Add documentation noting jig convert availability (from Jig v1.5.0) and what files it updates.
• Update the PDK→Jig command mapping table to include jig convert (instead of “not needed”) and fix table formatting.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

[miharp]

Filed #422 for fuller jig convert docs on the Jig reference page, follow-up, not
a blocker for this PR.

[miharp]

Was this delimiter change intentional?

It adds a space after each opening pipe but not before the closing one, so the
delimiter row no longer lines up with the header and body rows. As far as I can
tell this is the only table in docs/ shaped that way — 28 files use | --- |
and 7 use |---|.

It renders fine either way, so no real harm. Just wondering whether it's worth
reverting to keep the diff focused on the jig convert change?

[miharp]

Small wording suggestion to match the style guide: active voice and second person
per the tone guidelines, jig convert in monospace so it matches
the table row it explains, and one sentence per line like the surrounding paragraphs.

Suggested change

	For simplicity, a convert command was added to Jig starting with version 1.5.0. This allows you to automatically update your module's `Gemfile`, `Rakefile`, and `spec/spec_helper.rb` to OpenVox- and VoxBox-compatible versions.
	Jig 1.5.0 and later includes a `jig convert` command that migrates a PDK-based module for you.
	It rewrites the module's `Gemfile`, `Rakefile`, and `spec/spec_helper.rb` to OpenVox- and VoxBox-compatible versions.