docs(php-beginner): show the real router:list output in module 3

[miaulalala]

Follow-up to #48 (thanks @yard-mschwartz).

#48 fixed the command itself — there is no occ routes, it's router:list (core/Command/Router/ListRoutes.php:34). But the expected-output block underneath it was still wrong, so a reader who applies #48 hits a second mismatch immediately: router:list renders through writeTableInOutputFormat, i.e. a bordered Symfony table with route / request / path headers, not the borderless columns the module showed.

Also replaces | grep pinboard with the app-ID argument router:list accepts. Two reasons:

• grep strips the table headers, and
• with the full route list the column widths depend on every other enabled app, so the output can never be quoted reliably. With the app argument the table is stable and quotable.

Added a one-line note that routes sort alphabetically, since get_pins appearing before index otherwise looks like something is wrong.

⚠️ Needs a check against a real instance

The table in this PR is derived from the Symfony Table default style and the sort in ListRoutes::execute(), not copied from an actual run — I had no instance to run it against. The content is right; the exact border widths should be confirmed by pasting a real ./scripts/occ.sh nextcloud -- router:list pinboard before merging, otherwise we risk replacing one invented output block with another.

🤖 AI (if applicable)

• The content of this PR was partly or fully generated using AI