[totem/mallard-documentation] Move Plugins into Preferences, because that's where they are now

[Andre Klapper <aklapper src gnome org>]

commit 083ced7dfb51bf4091eef85a4d2315b6bb724fa7
Author: Andre Klapper <a9016009 gmx de>
Date:   Fri Jan 11 19:14:45 2019 +0100

    Move Plugins into Preferences, because that's where they are now

 help/C/plugins.page     | 32 --------------------------------
 help/C/preferences.page | 16 ++++++++++++++--
 help/meson.build        |  1 -
 3 files changed, 14 insertions(+), 35 deletions(-)
---
diff --git a/help/C/preferences.page b/help/C/preferences.page
index aa7200d5..932b1926 100644
--- a/help/C/preferences.page
+++ b/help/C/preferences.page
@@ -6,7 +6,7 @@
     <link type="guide" xref="index#application-adjustment"/>
     <link type="seealso" xref="subtitles"/>
     <revision pkgversion="3.30" version="0.2" date="2019-01-10" status="draft"/>
-    <desc>Configure the application.</desc>
+    <desc>Configure subtitles, audio and video output, and plugins.</desc>
     <credit type="author">
       <name>Marta Bogdanowicz</name>
       <email>majus85 gmail com</email>
@@ -20,7 +20,7 @@
     </license>
   </info>
 
-  <title>Preferences</title>
+  <title>Preferences and additional features</title>
 
   <p>
     <app>Videos</app> offers some additional options. Configure the
@@ -55,6 +55,18 @@
           <p><app>Videos</app> allows you to load chapter files when the movie is
           loaded. Do it by ticking this option.</p>
         </item>
+        <item>
+          <title><code>Plugins</code></title>
+          <p>Plugins offer extra featured and extend functionality. You can view
+          the list of plugins by pressing <gui style="button">Plugins…</gui>.
+          Select the the wanted one and press
+          <gui style="button">Preferences</gui> if available.</p>
+          <note style="tip">
+            <p>Notice that some options are available only if you fulfill some
+            requirements. For example, to use the <gui>BBC iPlayer</gui> plugin you
+            are supposed to be located in the United Kingdom.</p>
+          </note>
+        </item>
       </terms>
   </section>
 
diff --git a/help/meson.build b/help/meson.build
index da159840..bdcf754b 100644
--- a/help/meson.build
+++ b/help/meson.build
@@ -7,7 +7,6 @@ sources = [
   'playing-DVD.page',
   'playing-order.page',
   'playlist.page',
-  'plugins.page',
   'preferences.page',
   'properties.page',
   'screenshot-gallery.page',