README: suggest use of line folding (#82)

Co-authored-by: Joakim Sørensen <joasoe@gmail.com>

README.md

@@ -45,6 +45,8 @@ example:
 ## Ignore paths and names
 
 You can use the `ignore_paths` and `ignore_names` input to disable specific directories and files.
+These are passed as environment variables, and should evaluate to a single space-separated string.
+It may be convenient to use [`>-`](https://yaml.org/spec/1.2.2/#65-line-folding) for readability if you have multiple selectors.
 
 ```text
 sample structure:
@@ -61,7 +63,9 @@ example:
     - name: Run ShellCheck
       uses: ludeeus/action-shellcheck@master
       with:
-        ignore_paths: ignoreme ignoremetoo
+        ignore_paths: >-
+          ignoreme
+          ignoremetoo
         ignore_names: ignorable.sh
 ```