docs: improve accuracy of description

Signed-off-by: Mogyuchi <[email protected]>

README.md

@@ -5,19 +5,21 @@
 [![Check dist/](https://github.com/actions/typescript-action/actions/workflows/check-dist.yml/badge.svg)](https://github.com/actions/typescript-action/actions/workflows/check-dist.yml)
 [![CodeQL](https://github.com/actions/typescript-action/actions/workflows/codeql-analysis.yml/badge.svg)](https://github.com/actions/typescript-action/actions/workflows/codeql-analysis.yml)
 
-Souji Action deletes all GitHub Actions Caches created for branches related to
-the context of the triggered workflow event.
+Souji Action is a GitHub Action that deletes both the head ref and merge ref
+caches without any configuration.
 
 ## Usage
 
 `actions:write` permission is
 [required to delete caches](https://docs.github.com/en/rest/actions/cache?apiVersion=2022-11-28#delete-a-github-actions-cache-for-a-repository-using-a-cache-id).
 
 ```yml
+name: cleanup caches by a branch
 on:
-  pull_request:
+  pull_request_target:
     types:
       - closed
+  delete:
 
 jobs:
   cleanup:
@@ -29,8 +31,14 @@ jobs:
         uses: 4m-mazi/souji-action@v1 # Check and specify the latest version
 ```
 
-For instance, when a Pull Request created in the branch `feat/awesome-feature`
-is "merged" or "closed," a workflow event is triggered and the workflow is
-executed. At this time, all GitHub Actions Caches created under the merge ref
-`refs/pull/{pull_request_number}/merge` and the head ref
-`refs/heads/feat/awesome-feature` are deleted.
+This workflow cleans up caches for branches when they are merged(closed) or
+deleted.
+
+This will clear the following cache:
+
+- merge ref `refs/pull/<number>/merge`
+  - When a pull request is merged or closed, this workflow removes cached data
+    associated with the merge ref.
+- branch `<branch name>`
+  - When a branch is deleted, this workflow deletes the cached data associated
+    with the branch.