nix: rename custom -> packages

nix/custom/tokei/skel.patch

@@ -1,32 +0,0 @@
-diff --git a/languages.json b/languages.json
-index b2899f1..dfeff47 100644
---- a/languages.json
-+++ b/languages.json
-@@ -1406,6 +1406,10 @@
-       "quotes": [["\\\"", "\\\""]],
-       "extensions": ["shader", "cginc"]
-     },
-+    "Skel": {
-+      "multi_line_comments": [["(*", "*)"]],
-+      "extensions": ["skel", "sk"]
-+    },
-     "Slang": {
-       "name": "Slang",
-       "line_comment": ["//"],
-diff --git a/tests/data/skel.sk b/tests/data/skel.sk
-new file mode 100644
-index 0000000..c6e8a68
---- /dev/null
-+++ b/tests/data/skel.sk
-@@ -0,0 +1,11 @@
-+(* 11 lines 5 code 5 comments 1 blanks *)
-+
-+(* ^ a blank line, a comment *)
-+(*
-+a multiline comment
-+*)
-+type ident
-+type term =
-+| Var ident
-+| Lam (ident, term)
-+| App (term, term)