Add documentation snippet example

NOTE: I did not update the actual example, since that uses EuiText which overrides line-height, and is no longer a good example to demo lineHeight with

src-docs/src/views/datagrid/datagrid_height_options_example.js

@@ -26,6 +26,9 @@ const rowHeightsSnippet = `rowHeightsOptions = {
     4: 200, // for row which have index 4 we set 140 pixel
     5: 80,
   },
+  lineHeight: '1em', // default every cell line-height to 1em
+  // NOTE: if you wrap your cell content in CSS that overrides/sets line-height (e.g. in an EuiText),
+  // EuiDataGrid will not calculate row height correctly - make sure to match this to your used line height
 }`;
 
 const rowHeightsFullSnippet = `const rowHeightsOptions = useMemo(
@@ -122,6 +125,10 @@ export const DataGridRowHeightOptionsExample = {
             <EuiCode>rowHeights</EuiCode> - overrides the height for a specific
             row
           </li>
+          <li>
+            <EuiCode>lineHeight</EuiCode> - set a default line height for all
+            cells, which is also used to calculate row height
+          </li>
         </ul>
         <p>
           Each of these can be configured with an exact pixel height, a line