docs: publish the Function pages only once Functions launch

The two Function pages declare `launch: functions`, and every other page
marks what it says about Functions, so the assembled site leaves them out
until the launch. Before it, the pages that offered Functions for Python
work point Enterprise readers at Geneva instead.

The SQL Function example now uses Arrow type names, which the server
requires, and states the 3.12 default for `python_version`.

docs/web/sql/dml/refresh.mdx

@@ -52,11 +52,13 @@ REFRESH COLUMN embedding ON documents
 `num_workers` sets a count; the budget options size each worker. They are
 alternatives rather than a pair.
 
+{/* if functions launched */}
 <Note>
 `error_policy` and `num_workers` are refused for a column filled by a registered
 [function](/management/function) with its own resource budget -- use the CPU,
 memory and GPU options there.
 </Note>
+{/* end if */}
 
 ## REFRESH MATERIALIZED VIEW {#refresh-materialized-view}