tree-sitter: add cstrahan/tree-sitter-nix

pkgs/development/tools/parsing/tree-sitter/grammars/tree-sitter-nix.json

@@ -0,0 +1,10 @@
+{
+  "url": "https://github.com/cstrahan/tree-sitter-nix",
+  "rev": "791b5ff0e4f0da358cbb941788b78d436a2ca621",
+  "date": "2019-05-10T15:57:43-05:00",
+  "path": "/nix/store/5gcddcxf6jfr4f0p203jnbjc0zxk207d-tree-sitter-nix",
+  "sha256": "1y5b3wh3fcmbgq8r2i97likzfp1zp02m58zacw5a1cjqs5raqz66",
+  "fetchSubmodules": false,
+  "deepClone": false,
+  "leaveDotGit": false
+}

pkgs/development/tools/parsing/tree-sitter/update.nix

@@ -63,6 +63,10 @@ let
   # If you need a grammar that already exists in the official orga,
   # make sure to give it a different name.
   otherGrammars = {
+    "tree-sitter-nix" = {
+      orga = "cstrahan";
+      repo = "tree-sitter-nix";
+    };
     "tree-sitter-lua" = {
       orga = "nvim-treesitter";
       repo = "tree-sitter-lua";