readme: fix broken refernces

README.adoc

@@ -2279,14 +2279,14 @@ TODO we were not able to get it working yet: https://stackoverflow.com/questions
 
 === Linux kernel configuration
 
-==== Modify kernel config options
+==== Modify kernel config
 
 By default, we use a `.config` that is a mixture of:
 
 * Buildroot's minimal per machine `.config`, which has the minimal options needed to boot
 * our <<kernel-configs-about,kernel configs>> which enables options we want to play with
 
-If you want to just use your own exact `.config` instead, do:
+Use just your own exact `.config` instead:
 
 ....
 ./build -K data/myconfig -l
@@ -3762,7 +3762,7 @@ The hardware models can be either:
 +
 These have been explicitly designed to be educational rather than model real existing hardware.
 +
-But note that upstream [[edu]] device is also purely educational.
+But note that upstream <<edu>> device is also purely educational.
 
 ==== PCI
 
@@ -5743,7 +5743,7 @@ We have link:https://buildroot.org/downloads/manual/manual.html#ccache[enabled c
 
 ccache can considerably speed up builds when you:
 
-* are switching between multiple configurations for a given package to bisect something out, as mentioned at: <<use-your-own-kernel-config>>
+* are switching between multiple configurations for a given package to bisect something out, as mentioned at: <<modify-kernel-config>>
 * clean the build because things stopped working. We store the cache outside of this repository, so you can nuke away without fear
 
 The default ccache environment variables are honored if you have them set, which we recommend you do. E.g., in your `.bashrc`: