docs(options): update the EDIT and VIEW size limits

DC_MAXOBS_WEBEDIT 100 -> 250, DC_MAXOBS_WEBVIEW 500 -> 2000, and a new
DC_MAXCELLS_WEBEDIT (200000) which is applied together with the EDIT
observation limit - whichever is reached first.

docs/dcc-options.md

@@ -20,16 +20,23 @@ Currently used scopes include:
 ### DC_EMAIL_ALERTS
 Set to YES or NO to enable email alerts. This requires email options to be preconfigured (mail server etc).
 
+### 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.
+
+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
-By default, a maximum of 100 observations can be edited in the browser at one time.  This number can be increased, but note that the following factors will impact performance:
+By default, a maximum of 250 observations can be edited in the browser at one time.  This number can be increased, but note that the following factors will impact performance:
 
 * Number of configured [Validations](/dcc-validations)
 * Browser type and version (works best in Chrome)
 * Number (and size) of columns
 * Speed of client machine (laptop/desktop)
 
+A wide table can reach the [DC_MAXCELLS_WEBEDIT](#dc_maxcells_webedit) limit well before this one, so increase both together.
+
 ### DC_MAXOBS_WEBVIEW
-By default, a maximum of 500 observations can be viewed in the browser at one time. Please see previous section for items to consider if increasing this value.
+By default, a maximum of 2000 observations can be viewed in the browser at one time. Please see previous section for items to consider if increasing this value.
 
 ### DC_REQUEST_LOGS
 On SASjs Server and SAS9 Server types, at the end of each DC SAS request, a record is added to the [MPE_REQUESTS](/tables/mpe_requests) table.  In some situations this can cause table locks.  To prevent this issue from occuring, the `DC_REQUEST_LOGS` option can be set to `NO` (Default is `YES`).