improve docs for expliciting setting browser

for the console

h2/src/docsrc/html/tutorial.html

@@ -127,6 +127,11 @@ Depending on your platform and environment, there are multiple ways to start the
     </td>
 </tr>
 </table>
+<p>
+If the console startup procedure is unable to locate the default system web browser,
+an error message may be displayed. It is possible to explicitly tell H2 which
+program/script to use when opening a system web browser by setting either the BROWSER
+environment variable, or the h2.browser java property.
 
 <h3>Firewall</h3>
 <p>