Add information about automated cherry-picks (#2413)

Relies on PR #2410

Author: NataliaIvakina

README.adoc

@@ -35,3 +35,34 @@ When you run `npm start`, the project is monitored for updates to asciidoc files
 
 If a change to an asciidoc file is detected the site is automatically rebuilt.
 
+== Enable automatic cherry-picking on a PR
+
+To enable automatic cherry-picking on a PR, add the label `auto-cherry-pick` to it.
+Without it, the responsible GitHub action is not going to be triggered.
+
+To select the target branches you would like to cherry-pick your PR to, add labels of the following structure: `auto-cherry-pick-to-<targetBranch>`.
+For example: `auto-cherry-pick-to-main` to cherry-pick it to the branch `main` or `auto-cherry-pick-to-5.x` for the branch `5.x`.
+You may even add new labels for branches that do not have such a label yet.
+
+The feature is triggered by either merging a PR with the `auto-cherry-pick` label or by adding the `auto-cherry-pick` label to an already closed and merged PR.
+In the latter case, ensure that you first add the labels containing the target branches and then finally the `auto-cherry-pick` label.
+Otherwise the automation starts without any target branches.
+
+=== Details
+
+The PRs created by this GitHub action will have their heading prefixed with `[Cherry-pick][<targetBranch>]`.
+So, for example, for `main` as the target branch and `some changes` as the original PR heading, it results in `[Cherry-pick][main] some changes` as the heading for the cherry-picked PR.
+In case an assignee was set for the original PR, the cherry-picked PRs will also receive the same assignee.
+You must add reviewers manually after the cherry-picked PRs have been created.
+
+The creation of cherry-picked PRs can take a few minutes.
+If you are an assignee of the original PR, you receive an email notification once the cherry-picked PRs have been created.
+The original PR is updated with a comment that contains links to the newly created cherry-picked PRs.
+
+In case of a merge conflict while cherry-picking to a specific release branch, the branch will be skipped.
+Information on skipped branches is also included in the comment added to the original PR.
+In that case you have to take care of cherry-picking manually and resolve the conflicts.
+This is not going to influence the other release branches as long as they do not have conflicts.
+
+
+