[simple-scan] Update appdata.xml file with release information and fix warnings.

[Bartosz <bkosiorek src gnome org>]

commit 410b48d67278abc85badc337f834b2d3b86cf87d
Author: Bartosz Kosiorek <gang65 poczta onet pl>
Date:   Wed Sep 9 13:39:55 2020 +0200

    Update appdata.xml file with release information and fix warnings.
    
    Update comment of Lexmark scanner driver message.

 data/screenshots/simple-scan-1.png | Bin 0 -> 493727 bytes
 data/simple-scan.appdata.xml.in    |  26 ++++++++++++++++++++++++--
 src/app-window.vala                |   2 +-
 3 files changed, 25 insertions(+), 3 deletions(-)
---
diff --git a/data/screenshots/simple-scan-1.png b/data/screenshots/simple-scan-1.png
new file mode 100644
index 00000000..5468b256
Binary files /dev/null and b/data/screenshots/simple-scan-1.png differ
diff --git a/data/simple-scan.appdata.xml.in b/data/simple-scan.appdata.xml.in
index c9027e33..e2ab6c1a 100644
--- a/data/simple-scan.appdata.xml.in
+++ b/data/simple-scan.appdata.xml.in
@@ -16,13 +16,35 @@
     </p>
   </description>
   <screenshots>
-    <screenshot type="default">https://launchpadlibrarian.net/203209644/simple-scan.png</screenshot>
+    <screenshot type="default">
+      <image 
type="source">https://gitlab.gnome.org/GNOME/simple-scan/raw/master/data/screenshots/simple-scan-1.png</image>
+    </screenshot>
   </screenshots>
   <url type="homepage">https://gitlab.gnome.org/GNOME/simple-scan</url>
   <url type="bugtracker">https://gitlab.gnome.org/GNOME/simple-scan/issues</url>
-  <url type="donation">http://www.gnome.org/friends/</url>
+  <url type="donation">https://www.gnome.org/friends/</url>
   <developer_name>The GNOME Project</developer_name>
   <releases>
+    <release date="2020-09-11" version="3.38.0" type="development">
+      <description>
+        <p>
+          First stable release for GNOME 3.38, with the updated translations.
+        </p>
+      </description>
+    </release>
+    <release date="2020-09-04" version="3.37.92" type="development">
+      <description>
+        <p>
+          This is an unstable release in the 3.37 development series,
+          with the following improvements:
+        </p>
+        <ul>
+          <li>Display error message if simple-scan is unable to open simple-scan.log</li>
+          <li>Fix scanning on Epson devices, when Automatic Page Size is enabled</li>
+        </ul>
+        <p>This release also updates translations.</p>
+      </description>
+    </release>
     <release date="2019-09-08" version="3.34.0"/>
     <release date="2019-05-05" version="3.32.2.1"/>
     <release date="2019-04-09" version="3.32.2"/>
diff --git a/src/app-window.vala b/src/app-window.vala
index bc807465..67f10a8b 100644
--- a/src/app-window.vala
+++ b/src/app-window.vala
@@ -1671,7 +1671,7 @@ public class AppWindow : Gtk.ApplicationWindow
         case "lexmark_nscan":
             /* Message to indicate an Lexmark scanner has been detected */
             message = _("You appear to have an Lexmark scanner.");
-            /* Instructions on how to install Linux scanner drivers */
+            /* Instructions on how to install Lexmark scanner drivers */
             instructions = _("Drivers for this are available on the <a 
href=\"http://support.lexmark.com\";>Lexmark website</a>.");
             break;
         }