docs: add example for AWS ECR (#213)

Author: pat-s

.dictionary

@@ -16,3 +16,5 @@ drone-docker-buildx
 multiarch
 buildx
 DockerHub
+ECR
+GHCR

_docs/content/_index.md

@@ -56,6 +56,8 @@ steps:
 
 If the created image is to be pushed to registries other than the default DockerHub, it is necessary to set `registry` and `repo` as fully-qualified name.
 
+**GHCR**
+
 ```YAML
 kind: pipeline
 name: default
@@ -72,6 +74,27 @@ steps:
       tags: latest
 ```
 
+**AWS ECR**
+
+```YAML
+kind: pipeline
+name: default
+
+steps:
+  - name: docker
+    image: thegeeklab/drone-docker-buildx:23
+    privileged: true
+    environment:
+      AWS_ACCESS_KEY_ID:
+        from_secret: aws_access_key_id
+      AWS_SECRET_ACCESS_KEY:
+        from_secret: aws_secret_access_key
+    settings:
+      registry: <account_id>.dkr.ecr.<region>.amazonaws.com
+      repo: <account_id>.dkr.ecr.<region>.amazonaws.com/octocat/example
+      tags: latest
+```
+
 ## Build
 
 Build the binary with the following command: