DOCS-49013-Edit .backportrc.json file to reflect current versions

Author: mballard-mdb

.backportrc.json

@@ -1,11 +1,14 @@
 {
-  // Required
   "repoOwner": "mongodb",
   "repoName": "docs-java",
 
-  // the branches available to backport to
   "targetBranchChoices": [
     "master",
+    "v5.5",
+    "v5.4",
+    "v5.3",
+    "v5.2",
+    "v5.1",
     "v5.0",
     "v4.11",
     "v4.10",
@@ -18,7 +21,6 @@
     "v4.3"
   ],
 
-  // Optional: automatically merge backport PR
   "autoMerge": true,
   "autoMergeMethod": "squash"
 }