Cleanup dockerignore and readme

.dockerignore

@@ -1,2 +1,7 @@
 /.*
+/vendor
+/tests
+/Dockerfile
+/phpunit.xml
+/README.md
 

README.md

@@ -3,6 +3,17 @@
 This is a repository with an example application to test a custom docker pipeline
 using Gitea, Woodpecker and a private registry.
 
-- Runs phpunit against the code
+Dockerfile:
+
+- Runs composer install in temporary container
+- Launches hello, calling on a mock class
+
+Woodpecker:
+
+- Runs phpunit against the code, testing a mock function
 - Builds image from Dockerfile, tags the image and pushes to repo
 
+Define your secrets as:
+
+- `DOCKER_USERNAME`
+- `DOCKER_PASSWORD`