persist core.sshCommand for submodules (#184)

* persist core.sshCommand for submodules

* update verbiage; add comments

* fail when submodules or ssh-key and fallback to REST API

action.yml

@@ -16,7 +16,7 @@ inputs:
       commands. The post-job step removes the PAT.
 
 
-      We recommend creating a service account with the least permissions necessary.
+      We recommend using a service account with the least permissions necessary.
       Also when generating a new PAT, select the least scopes necessary.
 
 
@@ -24,12 +24,12 @@ inputs:
     default: ${{ github.token }}
   ssh-key:
     description: >
-      SSH key used to fetch the repository. SSH key is configured with the local
+      SSH key used to fetch the repository. The SSH key is configured with the local
       git config, which enables your scripts to run authenticated git commands.
       The post-job step removes the SSH key.
 
 
-      We recommend creating a service account with the least permissions necessary.
+      We recommend using a service account with the least permissions necessary.
 
 
       [Learn more about creating and using