auto-cherry-pick for docs-cypher (#1073)

@recrwplay changed the GitHub actions settings to include
"sorenlouv/backport-github-action@*,", not sure that's enough

---------

Co-authored-by: Neil Dewhurst <[email protected]>

Author: rsill-neo4j

.backportrc.json

@@ -0,0 +1,5 @@
+{
+    "repoOwner": "Neo4j",
+    "repoName": "docs-cypher",
+    "prTitle": "[Cherry-pick][{{targetBranch}}] {{commitMessages}}"
+}

.github/workflows/auto-backport.yml

@@ -0,0 +1,29 @@
+name: auto-cherry-pick
+on:
+  pull_request_target:
+    types: ["closed"]
+
+jobs:
+  backport:
+    name: Cherry-pick PR
+    runs-on: [ubuntu-latest]
+    if: |
+      github.event.pull_request.merged == true
+      && contains(github.event.pull_request.labels.*.name, 'cherry-pick')
+      && github.event.action == 'closed'
+      )
+    steps:
+      - name: Cherry-pick action
+        uses: sorenlouv/backport-github-action@929f69d04adbc196d982e60f02837b6cc00b3129
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          auto_backport_label_prefix: cherry-pick-to-
+          add_original_reviewers: false
+
+      - name: Info log
+        if: ${{ success() }}
+        run: cat ~/.backport/backport.info.log
+
+      - name: Debug log
+        if: ${{ failure() }}
+        run: cat ~/.backport/backport.debug.log

README.adoc

@@ -78,6 +78,36 @@ There are a few edge cases where we might want to work only on the current branc
 * When a new version is ready to published, the `5.x` branch will get a git tag, named with the exact version (for example, **5.1.0**), signifying that this point-in-time marks the completion of the work for that minor release.
 * Updates merged into the `dev` branch for the next release are cherry-picked into the `5.x` branch.
 
+=== 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-cypher-25` to cherry-pick it to the branch `cypher-25` 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 `6.x` as the target branch and `some changes` as the original PR heading, it results in `[Cherry-pick][6.x] 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 will 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.
+
+
 [[documenting-changes]]
 == Documenting changes to Cypher
 
@@ -117,3 +147,4 @@ When documenting a new Cypher feature, its relationship with GQL must be conside
 * If the feature is part of GQL's optional features, it should be recorded on the page xref:modules/ROOT/pages/appendix/gql-conformance/supported-optional.adoc[Supported optional GQL features].
 * if the feature adds functionality for which there exists an analogous, optional GQL feature, it should be recorded on the page xref:modules/ROOT/pages/appendix/gql-conformance/analogous-cypher.adoc[Optional GQL features and analogous Cypher].
 * If the feature adds functionality for which there exists no GQL equivalent, it should be recorded on the page xref:modules/ROOT/pages/appendix/gql-conformance/additional-cypher.adoc[Additional Cypher features].
+