Added positions for the about message (#1632)

My lint build fails because of this

leakcanary-android-core/src/main/res/values/leak_canary_strings.xml

@@ -18,7 +18,7 @@
   <string name="leak_canary_about_menu">About LeakCanary</string>
   <string name="leak_canary_about_title">About LeakCanary %s</string>
   <string name="leak_canary_about_message"><![CDATA[This is a dev extension for
-  <b>%s</b> (<i>%s</i>), automatically added by the LeakCanary library.<br><br>
+  <b>%1$s</b> (<i>%2$s</i>), automatically added by the LeakCanary library.<br><br>
   <a href="https://github.com/square/leakcanary">LeakCanary</a> is a memory leak detection library for Android, created
   and open source by <a href="https://twitter.com/Piwai">Pierre-Yves Ricau</a> at <a href="https://square.github.io">Square</a>.<br><br>
   You can learn more about memory leaks at <a href="https://squ.re/leaks">https://squ.re/leaks</a>.<br><br>