Fix welcome message

Author: rparrett

.github/workflows/welcome.yml

@@ -3,7 +3,10 @@ name: Welcome new contributors
 # This workflow has write permissions on the repo
 # It must not checkout a PR and run untrusted code
 
-on: pull_request_target
+on:
+  pull_request_target:
+    types:
+      - opened
 
 jobs:
   welcome:
@@ -38,5 +41,5 @@ jobs:
               repo: context.repo.repo,
               body: `**Welcome**, new contributor!
 
-                Please make sure you're read our [contributing guide](CONTRIBUTING.md) and we look forward to reviewing your Pull request shortly ✨`
+              Please make sure you're read our [contributing guide](https://github.com/bevyengine/bevy/blob/main/CONTRIBUTING.md) and we look forward to reviewing your Pull request shortly ✨`
             })