docs: updates to created-at, updated-at behaviour

Signed-off-by: Raju Udava <86527202+dstala@users.noreply.github.com>

packages/noco-docs/docs/070.fields/020.primary-key.md

@@ -15,7 +15,7 @@ As it uniquely identifies an individual record of a table, it is used internally
 Primary Key that gets defined / used in NocoDB depends on how underlying table was created. Summary is captured below
 1. From UI, Create new table / Import from Excel / Import from CSV
     1. An `ID` [datatype: Integer] system field created by default during table creation is used as primary key
-    2. Additional system fields `created-at`, `updated-at` are inserted by default & can be omitted optionally; these fields can be deleted after table creation
+    2. Additional system fields `created-at`, `updated-at` are inserted by default
 2. Connect to existing external database
     1. Existing `primary key` field defined for a table is retained as is; NocoDB doesn't insert a new ID field
     2. Additional system fields `created-at`, `updated-at` are not inserted by default