remove arg input again

it cannot deal with multiple arguments (bad) and fails if it's empty (even worse). Will have to check whether we can improve this action or whether the REUSE tool needs to adapt

README.md

@@ -40,24 +40,22 @@ jobs:
       uses: fsfe/reuse-action@master
 ```
 
-If you would like to provide extra arguments to the linter, or even run other subcommands, you could use the following snippet which outputs a the SPDX bill of materials including files in potential Git submodules:
+If you would like to run other subcommands, you could use the following snippet which outputs a the SPDX bill of materials:
 
 ```yml
     - name: REUSE Compliance Check
       uses: fsfe/reuse-action@master
       with:
         cmd: 'spdx'
-        arg: '--include-submodules'
 ```
 
-Please note that Github actions currently do not support an array of input arguments, so you can define only one value for `arg`.
+Please note that due to Github restrictions it is not possible to pass extra arguments like `--include-submodules` to the `cmd` input.
 
 ## Inputs Description
 
 | Name  | Requirement | Default | Description |
 | ----- | ----------- | ------- | ----------- |
 | `cmd` | _required_  | `lint`  | The subcommand for the REUSE helper tool. Read the [tool's documentation](https://reuse.readthedocs.io/) for all available subcommands. |
-| `arg` | _optional_  |         | Optional arguments for the REUSE helper tool. This action can only handle one argument at the moment due to design limitations. |
 
 ## License
 

action.yml

@@ -6,9 +6,6 @@ name: 'REUSE Compliance Check'
 description: "Check your project's REUSE compliance for clear and simple licensing and copyright!"
 author: 'Free Software Foundation Europe (FSFE)'
 inputs:
-  arg:
-    description: 'Optional argument'
-    required: false
   cmd:
     description: 'Subcommand'
     required: true
@@ -17,7 +14,6 @@ runs:
   using: 'docker'
   image: 'Dockerfile'
   args:
-    - ${{ inputs.arg }}
     - ${{ inputs.cmd }}
 branding:
   icon: 'check-circle'