Add nvim-lazy submodule and add plugin configuration.

pkgsets/nvim/lsp/yaml.nix

@@ -0,0 +1,24 @@
+{
+  lib,
+  config,
+  pkgs,
+  ...
+}:
+
+lib.optionalString (lib.elem "nvim::lsp::yaml" config.machine.pkgs) # lua
+  ''
+    lspconfig.yamlls.setup({
+      cmd = { "${pkgs.yaml-language-server}/bin/yaml-language-server", "--stdio" },
+      settings = {
+        yaml = {
+          schemaStore = {
+            -- Disable to use Store from SchemaStore-nvim plugin
+            enable = false,
+            -- Avoid TypeError: Cannot read properties of undefined (reading 'length')
+            url = "",
+          },
+          schemas = require('schemastore').yaml.schemas(),
+        },
+      },
+    })
+  ''