DOCSP-49013 .backportrc file creation (#101)

Author: mballard-mdb

.backportrc.json

@@ -0,0 +1,13 @@
+{
+  "repoOwner": "mongodb",
+  "repoName": "docs-kotlin-sync",
+
+  "targetBranchChoices": ["master", "v5.5", "v5.4", "v5.3", "v5.2", "v5.1", "v5.0", "v4.9", "v4.8", "v4.7", "v4.6", "v4.5", "v4.4", "v4.3"],
+
+  "autoMerge": true,
+  "autoMergeMethod": "squash",
+
+  "branchLabelMapping": {
+    "^auto-backport-to-(.+)$": "$1"
+  }
+}