updated README for github-pr plugin

Author: nick-codefresh

stable/github-pr/README.MD

@@ -10,3 +10,33 @@ Creates a new pull request in GitHub
 - `HEAD`: The name of the branch where your changes are implemented. For cross-repository pull requests in the same network, namespace head with a user like this: username:branch
 - `BASE`: The name of the branch you want the changes pulled into. This should be an existing branch on the current repository. You cannot submit a pull request to one repository that requests a merge to a base of another repository.
 - `TITLE`: The title of the pull request
+
+## Deployment with Codefresh
+- Add encrypted environment variables for:
+     * GITHUB_TOKEN
+
+- Add "github-pr" step as descibed below
+
+```yaml
+# codefresh.yml example with github pr step
+version: '1.0'
+
+steps:
+  build-step:
+    type: build
+    image-name: repo/image:tag
+
+  push to registry:
+    type: push
+    candidate: ${{build-step}}
+    tag: ${{CF_BRANCH}}
+
+  github-pr:
+    image: codefresh/github-pr-plugin
+    environment:
+      - GITHUB_REPO_OWNER=${{CF_REPO_OWNER}}
+      - GITHUB_REPO_NAME=${{CF_REPO_NAME}}
+      - BASE=master
+      - HEAD=${{CF_BRANCH}}
+      - TITLE=Codefresh PR for ${{CF_BRANCH}}
+```