Fix broken link

Fix the broken bootloader link in the english version as well. See also #749fe869cd63d0fb368f0857d613eee8e9f8bb79

docs/en/index.md

@@ -14,7 +14,7 @@ You need:
 The installation happens in four simple steps:
 
 1. Make sure that you are running at least [RoboPro Version 4.2.4](http://www.fischertechnik.de/ResourceImage.aspx?raid=10274)
-1. Enable the bootloader of your TXT by following the [official fischertechnik instructions](http://www.fischertechnik.de/en/ResourceImage.aspx?raid=10279)
+1. Enable the bootloader of your TXT by following the [official fischertechnik instructions](https://www.fischertechnik.de/-/media/fischertechnik/fite/service/downloads/robotics/txt-controller/documents/activation_bootloaders_english.ashx)
 1. Copy the contents of the [community firmware ZIP archive](https://github.com/ftCommunity/ftcommunity-TXT/releases/download/v0.9.3/ftcommunity-txt-0.9.3.zip) onto your sd card
 1. Insert the sd card into your TXT and switch it on!