docs: refactor

docs/manual/custom-plugins/configuring.md

@@ -0,0 +1,23 @@
+# Configuring {#configuring-plugins}
+
+Just making the plugin to your neovim configuration available might not always be enough.
+In that case, you can write custom vimscript or lua config, using `config.vim.configRC` or `config.vim.luaConfigRC`
+respectively. These options are attribute sets, and you need to give the configuration you're adding some name, like this:
+
+```nix
+{
+  # this will create an "aquarium" section in your init.vim with the contents of your custom config
+  # which will be *appended* to the rest of your configuration, inside your init.vim
+  config.vim.configRC.aquarium = "colorscheme aquiarum";
+}
+```
+
+:::{.note}
+If your configuration needs to be put in a specific place in the config, you can use functions from
+`inputs.neovim-flake.lib.nvim.dag` to order it.
+Refer to https://github.com/nix-community/home-manager/blob/master/modules/lib/dag.nix to find out more about
+the DAG system.
+:::
+
+Also, if you successfully made your plugin work, please make a PR to add it to the flake, or open an issue
+with your findings so that we can make it available for everyone easily.