Add topydo invocation and column UI screenshot in the welcome message

Now the screenshot is visible immediately when you visit the website.

doc/Documentation.html

@@ -6519,11 +6519,10 @@ Error message and password prompt
     }
 }</pre>
 </div>
-<div bag="default" created="20160425190954927" modified="20170111144508853" revision="0" title="$:/DefaultTiddlers" type="text/vnd.tiddlywiki">
+<div bag="default" created="20160425190954927" modified="20170719123138734" revision="0" title="$:/DefaultTiddlers" type="text/vnd.tiddlywiki">
 <pre>Welcome
 Features
 GettingStarted
-ScreenshotColumnUI
 Demo
 AboutTopydo
 Links</pre>
@@ -6659,19 +6658,19 @@ Links</pre>
 <div created="20170719121359752" modified="20170719121359752" title="$:/state/showeditpreview">
 <pre>yes</pre>
 </div>
-<div created="20170719122745581" modified="20170719122745581" title="$:/state/tab--1963855381">
-<pre>$:/core/ui/ControlPanel/Toolbars</pre>
+<div created="20170719122745581" modified="20170719122914472" title="$:/state/tab--1963855381">
+<pre>$:/core/ui/ControlPanel/Palette</pre>
 </div>
-<div created="20170719122741788" modified="20170719122741788" title="$:/state/tab-1749438307">
-<pre>$:/core/ui/ControlPanel/Appearance</pre>
+<div created="20170719122741788" modified="20170719122915728" title="$:/state/tab-1749438307">
+<pre>$:/core/ui/ControlPanel/Info</pre>
 </div>
-<div created="20170719121506797" modified="20170719122759388" title="$:/state/tab/sidebar--1835078512">
+<div created="20170719121506797" modified="20170719123156449" title="$:/state/tab/sidebar--1835078512">
 <pre>$:/core/ui/SideBar/Open</pre>
 </div>
 <div created="20170719122750165" modified="20170719122750925" title="$:/state/tabs/controlpanel/toolbars-1345989671">
 <pre>$:/core/ui/ControlPanel/Toolbars/PageControls</pre>
 </div>
-<div list="$:/ControlPanel Welcome Features GettingStarted ScreenshotColumnUI Demo AboutTopydo Links" title="$:/StoryList">
+<div list="Welcome Features GettingStarted Demo AboutTopydo Links" title="$:/StoryList">
 <pre></pre>
 </div>
 <div plugin-type="info" title="$:/temp/info-plugin" type="application/json">
@@ -8679,14 +8678,22 @@ The name of the tag can be overridden by {{!!tag-config}}.</pre>
 &lt;tr&gt;&lt;td&gt;&lt;$link to=&lt;&lt;currentTiddler&gt;&gt;&gt;&lt;&lt;currentTiddler&gt;&gt;&lt;/$link&gt;&lt;/td&gt;&lt;td&gt;{{!!summary}}&lt;/td&gt;&lt;/tr&gt;
 &lt;/$list&gt;</pre>
 </div>
-<div bag="default" created="20160425182240858" modified="20170118103150920" revision="0" title="Welcome" type="text/vnd.tiddlywiki">
+<div bag="default" created="20160425182240858" modified="20170719123328219" revision="0" title="Welcome" type="text/vnd.tiddlywiki">
 <pre>topydo is a powerful and customizable [[todo.txt|Format]] client for the console.
 
 Simply [[install|Installation]] with:
 
 ```
 pip3 install topydo
-```</pre>
+```
+
+and launch the column UI with:
+
+```
+topydo columns
+```
+
+{{ScreenshotColumnUI}}</pre>
 </div>
 
 </div>