adding a workflow to check files not ending in .sh

GitLab-CI.md

@@ -21,4 +21,17 @@ test:
     - git ls-files --exclude='*.sh' --ignored -c -z | xargs -0r shellcheck
 ```
 
+If you want to lint *all* shell scripts (i.e. with a shebang), even those not ending on `.sh`:
+
+```yaml
+test:
+    image: koalaman/shellcheck-alpine:latest
+    stage: test
+    before_script:
+    - apk update
+    - apk add git
+    script:
+    - git ls-files -c -z | xargs -0 awk -vORS='\0' 'FNR==1 && /^#!.*sh/ { print FILENAME }') | xargs -0r shellcheck
+```
+
 If you want to create a JUnit XML report to see in the GitLab's UI, check the instructions [here](JUnit), additionally checkstyle can also be [transformed](checkstyle2text) back into text again for logging purposes.