Changes kind of drone.yml to pipeline.

.drone.yml

@@ -1,9 +1,12 @@
-pipeline:
-  build-pdf:
+kind: pipeline
+name: default
+
+steps:
+  - name: build
     image: asciidoctor/docker-asciidoctor
     commands:
       - make pdf
-  release:
+  - name: release
     image: plugins/gitea-release
     settings:
       api_key:
@@ -11,4 +14,4 @@ pipeline:
       base_url: https://sources.grimbox.be
       files: source/main.pdf
     when:
-      event: tag
+      event: tag