ci: allow attestations in docker workflow

[skip ci]

Change-Id: I75baa6d4bbd156be7cc5b90e05b8d5d8bac20e5f
diff --git a/.github/workflows/docker.yml b/.github/workflows/docker.yml
index 9827007..b0cb3a8 100644
--- a/.github/workflows/docker.yml
+++ b/.github/workflows/docker.yml
@@ -2,15 +2,16 @@
 on:
   push:
     tags:
-      - 'ndn-tools-*'
+      - 'ndn-tools-[0-9]+*'
   schedule:
     # twice a month
     - cron: '20 10 5,20 * *'
   workflow_dispatch:
 
 permissions:
-  packages: write
+  attestations: write
   id-token: write
+  packages: write
 
 jobs:
   ndn-tools:
diff --git a/README.md b/README.md
index eee22fe..ae8c62a 100644
--- a/README.md
+++ b/README.md
@@ -3,6 +3,7 @@
 ![Latest version](https://img.shields.io/github/v/tag/named-data/ndn-tools?label=Latest%20version)
 ![Language](https://img.shields.io/badge/C%2B%2B-17-blue)
 [![CI](https://github.com/named-data/ndn-tools/actions/workflows/ci.yml/badge.svg)](https://github.com/named-data/ndn-tools/actions/workflows/ci.yml)
+[![Docker](https://github.com/named-data/ndn-tools/actions/workflows/docker.yml/badge.svg)](https://github.com/named-data/ndn-tools/actions/workflows/docker.yml)
 [![Docs](https://github.com/named-data/ndn-tools/actions/workflows/docs.yml/badge.svg)](https://github.com/named-data/ndn-tools/actions/workflows/docs.yml)
 
 This repository contains a collection of basic tools for [Named Data Networking (NDN)](https://named-data.net/).