make the UG sections links

en/userguide/_index.md

@@ -11,12 +11,12 @@ The user guide of the card10 is divided into a few sections. Here is an overview
  - Instructions how to assemble the card10
 
 ### [General usage](general-usage):
- - Buttons
- - Powering on
- - Expected run time
- - Going to standby
- - Powering off
- - Installing apps via USB
+ - [Buttons](general-usage#buttons)
+ - [Powering on](general-usage#powering-on)
+ - [Expected run time](general-usage#expected-run-time)
+ - [Going to standby](general-usage#going-to-standby)
+ - [Powering off](general-usage#powering-off)
+ - [Installing apps via USB](general-usage#installing-apps-via-usb)
 
 
 ### [Bluetooth Low Energy (BLE)](ble):