restore nvim as submodule (kickstart config); home-manager no longer owns nvim

Makefile

@@ -1,8 +1,8 @@
-.PHONY: all git shell tmux submodules p10k
+.PHONY: all nvim git shell tmux submodules p10k
 
 ZSH_CUSTOM ?= ${HOME}/.oh-my-zsh/custom
 
-all: submodules git shell tmux
+all: submodules nvim git shell tmux
 
 submodules:
 	git submodule update --init --recursive
@@ -10,6 +10,9 @@ submodules:
 git:
 	stow git -t ${HOME}
 
+nvim:
+	stow nvim -t ${HOME}/.config/
+
 shell: p10k
 	stow shell -t ${HOME}