Add email placeholders in documentation.

docs/jflow_advanced_configuration.html

@@ -194,7 +194,10 @@
 								<td>subject</td>
 								<td>-</td>
 								<td>The subject of the mail. This value will be used for all workflow. It can be overloaded within the
-									workflow implementation using <code>self.set_subject("subject")</code>
+									workflow implementation using <code>self.set_subject("subject")</code>.<br />
+									Placeholders can be used to access at the workflow attributes or unparametred methods: 
+									<code>###attribute###</code> or <code>###method()###</code>. For timestamps you can apply 
+									date function with syntax: <code>###attribute|date###</code> or <code>###method()|date###"</code>.
 								</td>
 							</tr>
 							
@@ -202,7 +205,10 @@
 								<td>message</td>
 								<td>-</td>
 								<td>The mail content. This value will be used for all workflow. It can be overloaded within the
-									workflow implementation using <code>self.set_message("message")</code>
+									workflow implementation using <code>self.set_message("message")</code>.<br />
+									Placeholders can be used to access at the workflow attributes or unparametred methods: 
+									<code>###attribute###</code> or <code>###method()###</code>. For timestamps you can apply 
+									date function with syntax: <code>###attribute|date###</code> or <code>###method()|date###"</code>.
 								</td>
 							</tr>
 						</tbody>

docs/jflow_core_workflow.html

@@ -851,7 +851,11 @@ bwamem = self.add_component("BWAmem", [bwaindex.databank, self.reads])</code></p
 									<td>string</td>
 									<td>true</td>
 									<td>None</td>
-									<td>The email subject to use for the email sent to the user once the workflow is completed.</td>
+									<td>The email subject to use for the email sent to the user once the workflow is completed.<br />
+										Placeholders can be used to access at the workflow attributes or unparametred methods: 
+										<code>###attribute###</code> or <code>###method()###</code>. For timestamps you can apply 
+										date function with syntax: <code>###attribute|date###</code> or <code>###method()|date###"</code>.
+									</td>
 								</tr>
 							</tbody>
 						</table>
@@ -879,7 +883,11 @@ bwamem = self.add_component("BWAmem", [bwaindex.databank, self.reads])</code></p
 									<td>string</td>
 									<td>true</td>
 									<td>None</td>
-									<td>The email message to use for the email sent to the user once the workflow is completed.</td>
+									<td>The email message to use for the email sent to the user once the workflow is completed.<br />
+										Placeholders can be used to access at the workflow attributes or unparametred methods: 
+										<code>###attribute###</code> or <code>###method()###</code>. For timestamps you can apply 
+										date function with syntax: <code>###attribute|date###</code> or <code>###method()|date###"</code>.
+									</td>
 								</tr>
 							</tbody>
 						</table>