nixos/doc: Fix outdated references in the NixOS manual

maryjane a6f14a60 40c36864

Changed files
+2 -2
nixos
doc
+2 -2
nixos/doc/manual/development/writing-documentation.chapter.md
···
[`nixos/doc/manual`](https://github.com/NixOS/nixpkgs/tree/master/nixos/doc/manual)
subdirectory of the Nixpkgs repository.
-
You can quickly validate your edits with `make`:
+
You can quickly validate your edits with `devmode`:
```ShellSession
$ cd /path/to/nixpkgs/nixos/doc/manual
$ nix-shell
-
nix-shell$ devmode
+
[nix-shell:~]$ devmode
```
Once you are done making modifications to the manual, it's important to