ensure dir is a subdir of curdir

Author: afirth

install/action.yml

@@ -14,6 +14,10 @@ inputs:
       Bash script to run after plugins are installed but before `asdf install`.
       eg, to install npm keyring
     required: false
+  directory:
+    description: |-
+      If present, the action will execute from this subdirectory
+    required: false
   asdf_branch:
     description: asdf branch to clone
     required: false