Update README to use pull_request_target event (#90)

Author: ylemkimon

README.md

@@ -2,8 +2,6 @@
 
 Pull request labeler triages PRs based on the paths that are modified in the PR.
 
-Note that only pull requests being opened from the same repository can be labeled.  This action will not currently work for pull requests from forks -- like is common in open source projects -- because the token for forked pull request workflows does not have write permissions.
-
 ## Usage
 
 ### Create `.github/labeler.yml`
@@ -84,7 +82,7 @@ Create a workflow (eg: `.github/workflows/labeler.yml` see [Creating a Workflow
 ```
 name: "Pull Request Labeler"
 on:
-- pull_request
+- pull_request_target
 
 jobs:
   triage: