Merge pull request #8901 from WiXSL/docs-datagrid-isrowselectable

Update Datagrid's `isRowSelectable` description and examples

Author: djhi

docs/Datagrid.md

@@ -62,7 +62,7 @@ Additional props are passed down to [the Material UI `<Table>` element](https://
 
 By default, `<Datagrid>` renders its body using `<DatagridBody>`, an internal react-admin component. You can pass a custom component as the `body` prop to override that default. And by the way, `<DatagridBody>` has a `row` prop set to `<DatagridRow>` by default for the same purpose. `<DatagridRow>` receives the row `record`, the `resource`, and a copy of the `<Datagrid>` children. That means you can create custom `<Datagrid>` logic without copying several components from the react-admin source.
 
-For instance, the `<Datagrid isRowSelectable>` prop allows to hide the selection checkbox for some records. To show a *disabled* checkbox instead of hiding it, you can override `<DatagridRow>` and `<DatagridBody>` as follows:
+For instance, the `<Datagrid isRowSelectable>` prop allows to disable the selection checkbox for some records. To *hide* checkboxes instead of disabling them, you can override `<DatagridRow>` and `<DatagridBody>` as follows:
 
 ```jsx
 // in src/PostList.js
@@ -74,12 +74,13 @@ const MyDatagridRow = ({ record, id, onToggleItem, children, selected, selectabl
         <TableRow>
             {/* first column: selection checkbox */}
             <TableCell padding="none">
-                <Checkbox
-                    disabled={selectable}
-                    checked={selected}
-                    onClick={event => onToggleItem(id, event)}
-                />
-            </TableCell>
+                {selectable && (
+                     <Checkbox
+                         checked={selected}
+                         onClick={event => onToggleItem(id, event)}
+                     />
+                )}
+            </TableCell>            
             {/* data columns based on children */}
             {React.Children.map(children, field => (
                 <TableCell key={`${id}-${field.props.source}`}>
@@ -581,9 +582,9 @@ const PostList = () => (
 
 ## `isRowSelectable`
 
-You can customize which rows show a selection checkbox using the `isRowSelectable` prop. It expects a function that receives the row record and returns a boolean.
+You can customize which rows show an enabled selection checkbox using the `isRowSelectable` prop. It expects a function that receives the row record and returns a boolean.
 
-For instance, this code shows a checkbox only for rows with an id greater than 300:
+For instance, this code enables a checkbox only for rows with an id greater than 300:
 
 ```jsx
 import { List, Datagrid } from 'react-admin';