add zod as dependency to specify version

Signed-off-by: Claire Casey <ccasey@spotify.com>

docs/permissions/plugin-authors/03-adding-a-resource-permission-check.md

@@ -91,7 +91,7 @@ This enables decisions based on characteristics of the resource, but it's import
 Install the missing module:
 
 ```bash
-$ yarn workspace @internal/plugin-todo-list-backend add @backstage/plugin-permission-node zod
+$ yarn workspace @internal/plugin-todo-list-backend add @backstage/plugin-permission-node
 ```
 
 Create a new `plugins/todo-list-backend/src/service/rules.ts` file and append the following code:

plugins/example-todo-list-backend/package.json

@@ -34,7 +34,8 @@
     "express-promise-router": "^4.1.0",
     "uuid": "^8.3.2",
     "winston": "^3.2.1",
-    "yn": "^4.0.0"
+    "yn": "^4.0.0",
+    "zod": "~3.18.0"
   },
   "devDependencies": {
     "@backstage/cli": "workspace:^",