Emit linkTitle and weight from the genref template (#1005)

The docs restructure in #989 added linkTitle and weight frontmatter to
the auto-generated API reference files, but the genref template does
not emit those fields, so make verify regenerates the files without
them and pull-lws-verify-main fails on the diff for any PR based on
current main.

Teach the template to emit both fields so the generated output matches
the checked-in files. No change to the generated files themselves.

Signed-off-by: Benjamin Braun <benjaminbraun@google.com>