docs(analytics): name the reference dimension class instead of listing two of its four members

`REFERENCE_VALUE_TYPES` is one class -- `lookup`, `master_detail`, `user`,
`tree` -- and all four store a related record's id and resolve to that
record's display name. Two authored pages enumerated only `lookup` /
`master_detail`, so a reader asking whether a person axis renders a name
read "no" off the enumeration.

Name the class in both sentences rather than growing the enumeration by two:
a prose list that mirrors a `const` is a second copy that drifts the next
time the set moves.

Claude-Session: https://claude.ai/code/session_017ef78bLdybu3AffehKkhfk
Co-authored-by: Claude <noreply@anthropic.com>

Author: claude

content/docs/data-modeling/analytics.mdx

@@ -208,7 +208,8 @@ The query result is presentation-ready — authors do not format dimension or
 measure values by hand:
 
 - **Dimensions** — a `select` dimension returns its option **label** (not the
-  stored value), a `lookup` / `master_detail` dimension returns the related
+  stored value), a **reference** dimension (any field whose stored value is
+  another record's id, a `user` person axis included) returns the related
   record's **display name** (not the FK id), and a `date` dimension with a
   `dateGranularity` returns a human bucket label (`month` → `2026-04`,
   `quarter` → `2026-Q2`, `year` → `2026`). Unresolved values pass through

content/docs/ui/dashboards.mdx

@@ -143,11 +143,13 @@ Notes on behaviour:
   truncates a reproducible window instead of an arbitrary subset.
 - Ordering is applied to the finished grid, so a **derived measure** is a valid
   `sortBy` even though no single SQL statement computes it.
-- A `sortBy` naming a **select** or **lookup** dimension orders by the
+- A `sortBy` naming a **select** or **reference** dimension orders by the
   **display label** the rows render (the option label / the related record's
   name), not the stored value or foreign-key id — and the label is resolved
-  before `limit` applies, so a top-N by name truncates the right N. Sorting by
-  a measure (the common case) involves no label lookup and is unaffected.
+  before `limit` applies, so a top-N by name truncates the right N.
+  **Reference** is the whole class of fields whose stored value is another
+  record's id, so a `user` person axis sorts by name too. Sorting by a measure
+  (the common case) involves no label lookup and is unaffected.
 - A `funnel` with no declared stage order falls back to sorting by value
   descending.