Bug 189316 Capitalize accesskey for Downloa_d_ More in content packs prefs

patch by piersc@cogs.susx.ac.uk r=dean_tessman sr=bz

extensions/content-packs/resources/locale/en-US/pref-contentpacks.dtd

@@ -5,7 +5,7 @@
 <!ENTITY restartOnLangChange.label      "Changes to content or language packs take effect when you restart &brandShortName;.">
 <!ENTITY installedContentPacks.label    "Installed content packs:">
 <!ENTITY installedLanguagePacks.label   "Installed language packs:">
-<!ENTITY downloadContentPacks.accesskey "d">
+<!ENTITY downloadContentPacks.accesskey "D">
 <!ENTITY downloadContentPacks.label     "Download More...">
 <!ENTITY update.label                   "(needs update)">
 <!ENTITY uninstallContentPack.accesskey "u">