Added file parameter as Dockerfile (#11)

## what
* Added `file` parameter as `Dockerfile`

Author: goruha

action.yml

@@ -9,6 +9,9 @@ inputs:
     description: 'Working directory'
     required: false
     default: './'
+  file:
+    description: 'Dockerfile name'
+    required: false 
   organization:
     description: 'Organization'
     required: true
@@ -65,6 +68,7 @@ runs:
       uses: docker/build-push-action@v2
       with:
         context: ${{ inputs.workdir }}
+        file: ${{ inputs.file }}
         pull: true
         push: true
         cache-from: type=gha