docs(options): the EDIT limits truncate the grid and warn

getdata no longer refuses a selection over DC_MAXOBS_WEBEDIT or
DC_MAXCELLS_WEBEDIT - it serves the rows within the limit and flags the
truncation against the table name.  Update the option reference and the two
developer-guide pages that claimed the edit screen stops with "Table is too
big".  The hook page also carried the old 500 row default.

docs/dcc-options.md

@@ -23,6 +23,8 @@ Set to YES or NO to enable email alerts. This requires email options to be preco
 ### DC_MAXCELLS_WEBEDIT
 By default, a maximum of 200,000 cells (observations multiplied by variables) can be edited in the browser at one time.  This limit is applied together with [DC_MAXOBS_WEBEDIT](#dc_maxobs_webedit) - whichever is reached first.
 
+A selection over either limit is served truncated: the grid carries the rows that fit, and a warning triangle next to the table name names the limit that was reached.  Filter the table to see the rest.
+
 The cell count matters because the cost of an EDIT screen load tracks the number of cells, not the number of rows.  A 10 column table is comfortable at 250 rows, but 250 rows of a 1000 column table is 250,000 cells.
 
 ### DC_MAXOBS_WEBEDIT