Merge pull request #29 from creative-commoners/pulls/1/docphp

DOC Document CMS major version detection

README.md

@@ -12,3 +12,9 @@ steps:
 ```
 
 This action has no inputs
+
+## CMS major version detection
+
+This action will identify the CMS major version which is determined by parsing the contents on the modules `composer.json` using logic in the `funcs.php` file. In cases where the major version remains indeterminable, the action will fail. This is most likely if the module is not intended as an addon for a website.
+
+To work around this, specify an arbitrary CMS major version by setting the required PHP version in `composer.json` to `^8.1` or any other minimum PHP version that aligns with a CMS major version.