Bring back "about" menu icon (#3329)

Author: UdjinM6

src/Makefile.qt.include

@@ -229,6 +229,7 @@ RES_ICONS = \
   qt/res/icons/tx_input.png \
   qt/res/icons/tx_output.png \
   qt/res/icons/tx_mined.png \
+  qt/res/icons/about.png \
   qt/res/icons/about_qt.png \
   qt/res/icons/verify.png \
   qt/res/icons/fontbigger.png \

src/qt/dash.qrc

@@ -44,6 +44,7 @@
         <file alias="filesave">res/icons/filesave.png</file>
         <file alias="debugwindow">res/icons/debugwindow.png</file>
         <file alias="browse">res/icons/browse.png</file>
+        <file alias="about">res/icons/about.png</file>
         <file alias="about_qt">res/icons/about_qt.png</file>
         <file alias="verify">res/icons/verify.png</file>
         <file alias="hd_enabled">res/icons/hd_enabled.png</file>