fix typo "logfile" -> "log file"

src/qt/forms/rpcconsole.ui

@@ -315,14 +315,14 @@
           </font>
          </property>
          <property name="text">
-          <string>Debug logfile</string>
+          <string>Debug log file</string>
          </property>
         </widget>
        </item>
        <item row="15" column="0">
         <widget class="QPushButton" name="openDebugLogfileButton">
          <property name="toolTip">
-          <string>Open the Bitcoin debug logfile from the current data directory. This can take a few seconds for large logfiles.</string>
+          <string>Open the Bitcoin debug log file from the current data directory. This can take a few seconds for large log files.</string>
          </property>
          <property name="text">
           <string>&amp;Open</string>