portfolio/page_editor: Update block chooser section

to update the screenshot and include the "Return to
pages and collections" button, which is new in
Mahara 17.10 (Bug #1688416).

source/portfolio/page_editor.rst

@@ -172,12 +172,19 @@ The *page layout area* is the place where you arrange all your content items for
    Drag a block into the page layout area and configure its settings
 
 #. Click on the block of the content item that you want to include in your page and drag it into the page layout area.
+
+   .. note::
+      If you navigate the site with a keyboard or long-click on the block, you see a pop-up modal in which you can choose the position of the block.
+
 #. When you see the dotted rectangle, drop the block into it to put it onto your page.
 #. Follow the on-screen instructions on choosing the specific content item you wish to display. Please refer to the :ref:`content block section <individual_artefact_blocks>` for more information on each block's settings.
 
 .. seealso::
    Please refer to the section :ref:`edit layout <edit_layout>` to learn how to change the number of columns and rows on a page and make certain columns wider than others.
 
+#. Click the *Display page* button to view your page without the editing tools.
+#. |new in Mahara 17.10| :index:`Click <single: New in Mahara 17.10; Button "Return to pages and collections" on page edit screen>` the *Return to pages and collections* button to go back to :ref:`the overview page for your portfolios <page>`.
+
 .. _page_edit_access:
 
 Edit access