about: thank Enzo GD in the About and Welcome dialogs

Enzo GD, administrator of the Olive Facebook user group, gave this
project generous promotional support in its early days. The shared body
text now carries a special-thanks line in both the About dialog and the
first-run Welcome dialog; zh_CN translation included.

app/dialog/about/about.cpp

@@ -65,6 +65,7 @@ AboutDialog::AboutDialog(bool welcome_dialog, QWidget *parent)
 					   "<p><b>%1</b> %2</p>" // AppName (version identifier)
 					   "<p>%3</p>" // Description
 					   "<p>%4</p>" // Fork notice
+					   "<p>%5</p>" // Special thanks
 					   "</body></html>")
 			.arg(
 				QApplication::applicationName(),
@@ -72,7 +73,10 @@ AboutDialog::AboutDialog(bool welcome_dialog, QWidget *parent)
 				tr("Oak Video Editor is a free open source non-linear video editor. "
 				   "This software is licensed under the GNU GPL Version 3."),
 				tr("This project is a fork of "
-				   "<a href=\"https://github.com/olive-editor/olive\">Olive Video Editor</a>.")));
+				   "<a href=\"https://github.com/olive-editor/olive\">Olive Video Editor</a>."),
+				tr("Special thanks to Enzo GD, administrator of the Olive "
+				   "Facebook user group, for his generous support in spreading "
+				   "the word about this project in its early days.")));
 
 	// Set text formatting
 	label->setAlignment(Qt::AlignLeft | Qt::AlignVCenter);

app/ts/zh_CN.ts

@@ -687,6 +687,10 @@ The possible range of CRF in SVT-AV1 is 1-63.</source>
         <source>About %1</source>
         <translation>关于 %1</translation>
     </message>
+    <message>
+        <source>Special thanks to Enzo GD, administrator of the Olive Facebook user group, for his generous support in spreading the word about this project in its early days.</source>
+        <translation>特别感谢 Olive Facebook 用户群组管理员 Enzo GD，在项目早期为宣传推广所给予的慷慨支持。</translation>
+    </message>
     <message>
         <location line="+29" />
         <source>Oak Video Editor is a free open source non-linear video editor. This software is licensed under the GNU GPL Version 3.</source>