Use fewer note styles

doc/topics/autodevops/index.md

@@ -766,10 +766,17 @@ or a `.buildpacks` file in your project:
   and add the URL of the buildpack to use on a line in the file. If you want to
   use multiple buildpacks, you can enter them in, one on each line.
 
-CAUTION: **Caution:**
-Using multiple buildpacks isn't yet supported by Auto DevOps.
+#### Multiple buildpacks
+
+Using multiple buildpacks isn't fully supported by Auto DevOps because, when using the `.buildpacks`
+file, Auto Test will not work.
+
+The buildpack [heroku-buildpack-multi](https://github.com/heroku/heroku-buildpack-multi/),
+which is used under the hood to parse the `.buildpacks` file, doesn't provide the necessary commands
+`bin/test-compile` and `bin/test`.
 
-CAUTION: **Caution:** When using the `.buildpacks` file, Auto Test will not work. The buildpack [heroku-buildpack-multi](https://github.com/heroku/heroku-buildpack-multi/) (which is used under the hood to parse the `.buildpacks` file) doesn't provide the necessary commands `bin/test-compile` and `bin/test`. Make sure to provide the project variable `BUILDPACK_URL` instead.
+If your goal is to use only a single custom buildpack, you should provide the project variable
+`BUILDPACK_URL` instead.
 
 ### Custom `Dockerfile`