change rollover rest-api placeholder name

rest-api-spec/src/main/resources/rest-api-spec/api/indices.rollover.json

@@ -3,10 +3,10 @@
     "documentation": "http://www.elastic.co/guide/en/elasticsearch/reference/master/indices-rollover-index.html",
     "methods": ["POST"],
     "url": {
-      "path": "/{index}/_rollover",
-      "paths": ["/{index}/_rollover"],
+      "path": "/{alias}/_rollover",
+      "paths": ["/{alias}/_rollover"],
       "parts": {
-        "index": {
+        "alias": {
           "type" : "string",
           "required" : true,
           "description" : "The name of the alias to rollover"

rest-api-spec/src/main/resources/rest-api-spec/test/indices.rollover/10_basic.yaml

@@ -31,7 +31,7 @@
   # perform alias rollover
   - do:
     indices.rollover:
-      index: "logs_search"
+      alias: "logs_search"
       body:
         conditions:
           max_docs: 1