c_per_game: Inform when settings might not be configurable

src/yuzu/configuration/configure_per_game.ui

@@ -2,6 +2,14 @@
 <ui version="4.0">
  <class>ConfigurePerGame</class>
  <widget class="QDialog" name="ConfigurePerGame">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>900</width>
+    <height>607</height>
+   </rect>
+  </property>
   <property name="minimumSize">
    <size>
     <width>900</width>
@@ -224,6 +232,15 @@
      </item>
     </layout>
    </item>
+   <item>
+    <layout class="QHBoxLayout" name="horizontalLayout_2">
+     <item>
+      <widget class="QLabel" name="label_8">
+       <property name="text">
+        <string>Some settings are only available when a game is not running.</string>
+       </property>
+      </widget>
+     </item>
      <item>
       <widget class="QDialogButtonBox" name="buttonBox">
        <property name="sizePolicy">
@@ -241,6 +258,8 @@
       </widget>
      </item>
     </layout>
+   </item>
+  </layout>
  </widget>
  <resources/>
  <connections>