docs: Remove extra typing for Column Defs when using helper (#4430)

When using an `accessor` type column helper in a top level column defs array where the array is also typed, you get the type error mentioned in #4382. It was mentioned that the solution here is to not type the array, so this PR removes the typing from the example in the docs.

Author: csandman

docs/guide/column-defs.md

@@ -46,7 +46,7 @@ type Person = {
 const columnHelper = createColumnHelper<Person>()
 
 // Make some columns!
-const defaultColumns: ColumnDef<Person>[] = [
+const defaultColumns = [
   // Display Column
   columnHelper.display({
     id: 'actions',