add clarification about output usage hygiene

README.md

@@ -170,6 +170,17 @@ The Dependency Review GitHub Action check will only block a pull request from be
 > [!NOTE]
 > Action outputs are unicode strings [with a 1MB size limit](https://docs.github.com/en/actions/creating-actions/metadata-syntax-for-github-actions#outputs-for-docker-container-and-javascript-actions).
 
+> [!IMPORTANT]
+> If you use these outputs in a run-step, you must store the ouput data in an envrioment variable instead of using the output directly. Using an output directly might break shell scripts. For example:
+>
+> ```yaml
+> env:
+>   VULNERABLE_CHANGES: ${{ steps.review.outputs.vulnerable-changes }}
+> run: echo "$VULNERABLE_CHANGES" | jq
+> ```
+>
+> instead of direct `echo '${{ steps.review.outputs.vulnerable-changes }}'`. See [examples](docs/examples.md) for more.
+
 ## Getting help
 
 If you have bug reports, questions or suggestions please [create a new issue](https://github.com/actions/dependency-review-action/issues/new/choose).

docs/examples.md

@@ -193,7 +193,7 @@ jobs:
         # make sure this step runs even if the previous failed
         if: ${{ failure() && steps.review.conclusion == 'failure' }}
         shell: bash
-        env:
+        env: # store comment HTML data in an environment variable
           COMMENT: ${{ steps.review.outputs.comment-content }}
         run: | # do something with the comment:
           echo "$COMMENT"
@@ -201,7 +201,7 @@ jobs:
         # make sure this step runs even if the previous failed
         if: ${{ failure() && steps.review.conclusion == 'failure' }}
         shell: bash
-        env:
+        env: # store JSON data in an environment variable
           VULNERABLE_CHANGES: ${{ steps.review.outputs.vulnerable-changes }}
         run: | # do something with the JSON:
           echo "$VULNERABLE_CHANGES" | jq '.[].package_url'