docs(derived): mark the page as draft so it can merge before the release

A warning banner on both pages, and '(draft)' in the navigation title, so a
reader is not surprised when the feature is not in their installed version.
Remove both when the release carrying derived variables goes out.

mkdocs build passes; the banner and all four images render.

docs/derived-variables.md

@@ -6,6 +6,11 @@ description: Derived variables are computed columns that appear in the EDIT scre
 
 # Derived Variables
 
+!!! warning "Draft - not in a release yet"
+    This page describes a feature that is in development. It is published early so
+    the wording and the screenshots can be reviewed; the behaviour described here
+    ships in the next release.
+
 A derived variable is a column that does not exist in the target table, but is computed when the table is loaded into the [EDIT screen](/dc-userguide/#editor). It is read-only, it appears after the physical columns, and it can be filtered on like any other column.
 
 Derived variables are useful when users need to work with a value that is a function of the stored data - a banding, a concatenation, a calculation - without changing the table, the load process, or the ETL.

docs/tables/mpe_derived.md

@@ -6,6 +6,11 @@ description: The MPE_DERIVED table is used to configure computed columns that ap
 
 # MPE_DERIVED
 
+!!! warning "Draft - not in a release yet"
+    This page describes a feature that is in development. It is published early so
+    the wording and the screenshots can be reviewed; the behaviour described here
+    ships in the next release.
+
 The MPE_DERIVED table is used to configure derived (computed) variables - columns that are created when a table is loaded into the EDIT screen, so that they can be displayed and filtered on without being stored.  More details are available in the [user guide](/derived-variables/)
 
 The table is itself registered in [MPE_TABLES](/tables/mpe_tables/), so it is maintained through the EDIT screen with the usual review and approve workflow.

mkdocs.yml

@@ -32,7 +32,7 @@ nav:
     - MPE_DATASTATUS_TABS: tables/mpe_datastatus_tabs.md
     - MPE_DATADICTIONARY: tables/mpe_datadictionary.md
     - MPE_DATALOADS: tables/mpe_dataloads.md
-    - MPE_DERIVED: tables/mpe_derived.md
+    - MPE_DERIVED (draft): tables/mpe_derived.md
     - MPE_EMAILS: tables/mpe_emails.md
     - MPE_EXCEL_CONFIG: tables/mpe_excel_config.md
     - MPE_FILTERANYTABLE: tables/mpe_filteranytable.md
@@ -59,7 +59,7 @@ nav:
     - CAS Tables: cas-tables.md
     - Column Level Security: column-level-security.md
     - Dates / Datetimes: dcc-dates.md
-    - Derived Variables: derived-variables.md
+    - Derived Variables (draft): derived-variables.md
     - Dynamic Cell Dropdown: dynamic-cell-dropdown.md
     - Emails: emails.md
     - Excel: excel.md