ENH Add branches to supported modules list (#22)

README.md

@@ -5,9 +5,14 @@ Used to generate the
 and is the starting point for tooling such as
 our ["Elvis" bug tracker](https://github.com/silverstripe/github-issue-search-client).
 
-It's known to be used for the following modules:
-- silverstripe/tx-translator
-- bringyourownideas/silverstripe-maintainence
+Each branch of this repository represents a major release line of Silverstripe CMS. You can fetch the JSON for the relevant release line by simply fetching the raw copy of `modules.json` for a given release branch, e.g. https://raw.githubusercontent.com/silverstripe/supported-modules/5/modules.json
+
+It's known to be used in the following repositories:
+
+- [silverstripe/cow](https://github.com/silverstripe/cow)
+- [silverstripe/tx-translator](https://github.com/silverstripe/silverstripe-tx-translator/)
+- [bringyourownideas/silverstripe-maintainence](https://github.com/bringyourownideas/silverstripe-maintenance)
+- [silverstripe/github-issue-search-client](https://github.com/silverstripe/github-issue-search-client)
 
 ## Format
 
@@ -17,8 +22,10 @@ It's known to be used for the following modules:
  * `scrutinizer`: Boolean. Does this repo have Scrutinizer enabled?
  * `addons`: Boolean. Does this module exist on addons.silverstripe.org?
  * `type`: String. `supported-module` or `supported-dependency`
- * `githubId` Number. The [id](https://docs.github.com/en/rest/reference/repos#get-a-repository) in Github. Used as a unique identifier.
- * `isCore`. Boolean. Is this considered a direct dependency of `silverstripe/installer`, `silverstripe/recipe-cms` or `silverstripe/recipe-core`?
+ * `githubId`: Number. The [id](https://docs.github.com/en/rest/reference/repos#get-a-repository) in Github. Used as a unique identifier.
+ * `isCore`: Boolean. Is this considered a direct dependency of `silverstripe/installer`, `silverstripe/recipe-cms` or `silverstripe/recipe-core`?
+ * `branches`: Array<String>. All major branches in lowest-to-heighest order (e.g. `["3", "4"]`, not `["4", "4.12"]`) of this module which are officially supported for this major release line of Silverstripe CMS. E.g. silverstripe/graphql was supported for `3` and `4` for the CMS 4 major release line.
+   * Systems using the branches array need to be smart enough to check for last-minor branches if the branch in the list is missing from github (e.g. if `4` is missing, fetch the list of branches for that repository from the github API and use the latest `4.x` (e.g. `4.13`) branch).
 
 ## Adding a repo