Expanding the documentation.

.github/workflows/changelog.yml

@@ -8,7 +8,7 @@ jobs:
       # To use this repository's private action, you must check out the repository
       - name: Checkout
         uses: actions/checkout@v2
-      # Fetch all tags
+      # By default the checkout is shallow. Fetch all tags, branches, and history.
       - run: |
           git fetch --depth=1 origin +refs/tags/*:refs/tags/*
           git fetch --no-tags --prune --depth=1 origin +refs/heads/*:refs/remotes/origin/*

README.md

@@ -20,13 +20,25 @@ Markdown formatted changelog.
 
 ## Example usage
 
+There are three blocks you will need. The first is an additional run block after your checkout. By default an action checkout is shallow. So add:
+
+    - name: Checkout
+      uses: actions/checkout@v2
+    # By default the checkout is shallow. Fetch all tags, branches, and history.
+    - run: |
+        git fetch --depth=1 origin +refs/tags/*:refs/tags/*
+        git fetch --no-tags --prune --depth=1 origin +refs/heads/*:refs/remotes/origin/*
+        git fetch --prune --unshallow
+
+Next you will need to generate the changelog itself. To get the changelog between the SHA of the commit that triggered the action and the tag of the latest release:
+
     - name: Generate changelog
       id: changelog
       uses: metcalfc/changelog-generator@v0.0.1
       with:
         myToken: ${{ secrets.GITHUB_TOKEN }}
 
-Or
+Or if you have two specific references you want:
 
     - name: Generate changelog
       id: changelog
@@ -36,4 +48,9 @@ Or
         head-ref: 'v0.0.2'
         base-ref: 'v0.0.1'
 
+Lastly you need to use the changelog.
+
+    - name: Get the changelog
+      run: echo "${{ steps.changelog.outputs.changelog }}"
+
 Why do we need `myToken`? Read more here: https://help.github.com/en/actions/automating-your-workflow-with-github-actions/authenticating-with-the-github_token#about-the-github_token-secret