Cleanup README

Remove sections on building depot and make targets as it is no
longer valid.

README.md

@@ -56,7 +56,7 @@ instructions for enabling: https://app.cachix.org/cache/genodepkgs
 ```sh
 $ git clone https://git.sr.ht/~ehmry/genodepkgs
 $ cd genodepkgs
-$ nix build .#checks.x86_64-linux.nova-x86
+$ nix build -L .#checks.x86_64-linux.nova-x86
 
 # View the log if the result is already cached:
 $ nix log .#checks.x86_64-linux.nova-x86
@@ -94,25 +94,10 @@ x86_64-unknown-genode-clang++ -v
 
 # Tips and tricks
 
-## How to build a Genode make target?
-
-```nix
-let flake = builtins.getFlake "genodepkgs";
-in flake.packages.x86_64-linux-x86_64-genode.genodeSources.make "app/ping"
-```
-
-## How to build a Genode depot package?
-
-```nix
-let flake = builtins.getFlake "genodepkgs";
-in flake.packages.x86_64-linux-x86_64-genode.genodeSources.depot "wifi_drv"
-```
-
 ## How to add missing ports to a depot package?
 
 The missing ports as indicated by a depot build failure must be added to
-[targets.nix](./overlay/genode/targets.nix). To continue from the previous
-example, this would be sufficient:
+[targets.nix](./overlay/genode/targets.nix). For example:
 
 ```nix
 {