Update descriptions in README.md and action.yml

Co-authored-by: Jan Amann <jan@amann.me>
Signed-off-by: Kenji Miyake <kenji.miyake@tier4.jp>

README.md

@@ -77,10 +77,8 @@ The action works without configuration, however you can provide options for cust
           # merge commit, and it's easy to commit this by mistake. Enable this option
           # to also validate the commit message for one commit PRs.
           validateSingleCommit: true
-          # When using "validateSingleCommit", even if you edit the PR title, the PR
-          # title is not used for the merge commit. Also, since it cannot detect an error
-          # as long as the commit message is semantic, it's easy to commit this by mistake.
-          # Enable this option to also validate if the PR title matches the commit title.
+          # Related to `validateSingleCommit` you can opt-in to validate that the PR
+          # title matches a single commit to avoid confusion.
           validateSingleCommitMatchesPrTitle: true
           # If you use Github Enterprise, you can set this to the URL of your server
           githubBaseUrl: https://github.myorg.com/api/v3

action.yml

@@ -30,7 +30,7 @@ inputs:
     description: "When using \"Squash and merge\" on a PR with only one commit, GitHub will suggest using that commit message instead of the PR title for the merge commit, and it's easy to commit this by mistake. Enable this option to also validate the commit message for one commit PRs." 
     required: false
   validateSingleCommitMatchesPrTitle:
-    description: "When using \"validateSingleCommit\", even if you edit the PR title, the PR title is not used for the merge commit. Also, since it cannot detect an error as long as the commit message is semantic, it's easy to commit this by mistake. Enable this option to also validate if the PR title matches the commit title."
+    description: "Related to `validateSingleCommit` you can opt-in to validate that the PR title matches a single commit to avoid confusion."
     required: false
   githubBaseUrl:
     description: "If you use Github Enterprise, you can set this to the URL of your server (e.g. https://github.myorg.com/api/v3)"