docs(website): document the seed command, with cast (ADR-0048)

New Reference page "Generating sample data" (captured output + a
two-table seed cast showing generation, FK sampling context, and a
`set` override); cross-links from inserting-and-editing-data and
columns; seed added to the rdbms highlight grammar;
querying/sql-queries renumbered. Cast stance in STYLE.md revised to
"justify the absence". Refs #33, #34.

website/src/content/docs/reference/inserting-and-editing-data.md

@@ -113,5 +113,8 @@ update <Table> set <col>=<value>[, ...] (where <expr> | --all-rows)
 delete from <Table> (where <expr> | --all-rows)
 ```
 
+To fill a table with many rows at once instead of typing each one, see
+[Generating sample data](/reference/generating-sample-data/).
+
 See also [Querying & inspecting](/reference/querying-and-inspecting/) and
 [Constraints](/reference/constraints/).