📖 DOC: update READ.ME with using Doppler instructions

Author: ommyjay

README.md

@@ -60,3 +60,63 @@ with:
     commit_user_email: '[email protected]'
 
 ```
+
+### Use with Doppler
+
+> NOTE:
+Author's doppler.com configuration token should be set as an secret variable in your GitHub repository with the name of the author followed by _DOPPLER_TOKEN.
+
+```bash
+      - name: Set up doppler CLI
+        uses: dopplerhq/cli-action@v1
+
+      - name: Set up author doppler token env variable
+        run: |
+          dopplerToKenName=$(echo "${GITHUB_ACTOR}_DOPPLER_TOKEN" | tr '[:lower:]' '[:upper:]')
+          echo "DOPPLER_TOKEN=$dopplerToKenName" >> $GITHUB_ENV
+
+      - name: Set up cross-post env variables from doppler
+        run: |
+          doppler run -- printenv | grep DOPPLER
+          echo "DEVTO_API_KEY=$(doppler secrets get DEVTO_API_KEY --plain)" >> $GITHUB_ENV
+          echo "DEVTO_ORG_ID=$(doppler secrets get DEVTO_ORG_ID --plain)" >> $GITHUB_ENV
+          echo "MEDIUM_API_KEY=$(doppler secrets get MEDIUM_API_KEY --plain)" >> $GITHUB_ENV
+          echo "MEDIUM_BLOG_ID=$(doppler secrets get MEDIUM_BLOG_ID --plain)" >> $GITHUB_ENV
+          echo "HASHNODE_API_KEY=$(doppler secrets get HASHNODE_API_KEY --plain)" >> $GITHUB_ENV
+          echo "HASHNODE_BLOG_ID=$(doppler secrets get HASHNODE_BLOG_ID --plain)" >> $GITHUB_ENV
+        env:
+          DOPPLER_TOKEN: ${{ secrets[env.DOPPLER_TOKEN] }}
+
+...
+
+      uses: ommyjay/blogs-cross-post-action-for-teams@v1
+      id: cross_post
+      with:
+        with:
+          files_location: 'posts/**/*.md'
+          dry_run: 'true'
+          publish: 'false'
+          devto_api_key: ${{ env.DEVTO_API_KEY }}
+          medium_api_key: ${{ env.MEDIUM_API_KEY }}
+          devto_org_id: ${{ env.DEVTO_ORG_ID }}
+          medium_blog_id: ${{ env.MEDIUM_BLOG_ID}}
+          hashnode_api_key: ${{ env.HASHNODE_API_KEY }}
+          hashnode_blog_id: ${{ env.HASHNODE_BLOG_ID }}
+
+      - name: Clean up changed files
+        run: git rm `git ls-files --deleted` || exit 0;
+
+      - name: Commit new files
+        uses: stefanzweifel/git-auto-commit-action@v4
+        with:
+          commit_message: '⚙️ AUTOMATED: Add posted articles files ${{ steps.cross_post.outputs.posted_articles }}'
+          file_pattern: posts/**/*.md
+          commit_user_name: ommyjay
+          commit_user_email: '[email protected]'
+```
+
+### TODO
+
+- [ ] Create a separate Doppler action to retrieve Author's doppler.com configuration token
+- [ ] Handle post cross-posting git cleanup steps within the action
+- [ ] Handle post cross-posting git commit steps within the action