docs(cloud): thread titles example names the generateTitle handler regenerate

the example in apps/docs/content/docs/cloud/(conversations)/thread-titles.mdx (lines 94 and 99) binds aui.threadListItem().generateTitle() to a handler named regenerate, while the paragraph right under it says that on a thread that already has a title the call receives that title again, unchanged.

the name suggests the call replaces a title, which the cloud endpoint never does (see #7023). naming the handler after what it does, for example generateTitle, keeps the example consistent with the documented contract.