neovim/queries: init and add an example injection

docs/manual/configuring/queries.md

@@ -0,0 +1,46 @@
+# Queries (`vim.treesitter.queries`)
+
+Queries allow you to change Neovim's behavior based on Tree-sitter.\
+Read more about it in the
+[neovim docs](https://neovim.io/doc/user/treesitter/#_treesitter-queries).
+
+**Example:**
+
+In the following example, we are creating a custom injection, to highlight the
+Lua string after `mkLuaInline`.
+
+```nix
+foo = mkLuaInline ''
+  function bar()
+    return 'foobar'
+  end
+'';
+```
+
+```nix
+{
+  vim.treesitter.queries = [{
+    type = "injections";
+    filetypes = ["nix"];
+    content = ''
+      ;; extends
+
+      ((apply_expression
+        function: (variable_expression
+          name: (identifier) @_func
+          (#eq? @_func "mkLuaInline"))
+
+        argument: (indented_string_expression
+          (string_fragment) @injection.content)
+
+        (#set! injection.language "lua")
+        (#set! injection.combined)))
+    '';
+  }];
+}
+```
+
+This will generate a `queries/nix/injections.scm` in a Neovim runtime directory.
+
+> [!NOTE]
+> When multiple queries match the same `filetype` and `type`, they are merged.