Add backport bot configuration

Author: mark-vieira

.backportrc.json

@@ -0,0 +1,14 @@
+{
+ "upstream": "elastic/elasticsearch-java",
+ "targetBranchChoices": [
+ "master",
+ "8.0",
+ "7.17",
+ "7.16"
+ ],
+ "targetPRLabels": ["backport"],
+ "branchLabelMapping": {
+ "^v8.1.0$": "master",
+ "^v(\\d+).(\\d+).\\d+(?:-(?:alpha|beta|rc)\\d+)?$": "$1.$2"
+ }
+}