adding and fixing rest-api-spec files

Author: masseyke

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

@@ -0,0 +1,36 @@
+{
+  "indices.get_data_stream_mappings":{
+    "documentation":{
+      "url":"https://www.elastic.co/guide/en/elasticsearch/reference/master/data-streams.html",
+      "description":"Gets a data stream's mappings"
+    },
+    "stability":"stable",
+    "visibility": "feature_flag",
+    "feature_flag": "logs_stream",
+    "headers":{
+      "accept": [ "application/json"]
+    },
+    "url":{
+      "paths":[
+        {
+          "path":"/_data_stream/{name}/_mappings",
+          "methods":[
+            "GET"
+          ],
+          "parts":{
+            "name":{
+              "type":"string",
+              "description":"Comma-separated list of data streams or data stream patterns"
+            }
+          }
+        }
+      ]
+    },
+    "params":{
+      "master_timeout":{
+        "type":"time",
+        "description":"Period to wait for a connection to the master node"
+      }
+    }
+  }
+}

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

@@ -20,7 +20,7 @@
           "parts":{
             "name":{
               "type":"string",
-              "description":"The name of the data stream or data stream pattern"
+              "description":"Comma-separated list of data streams or data stream patterns"
             }
           }
         }
@@ -29,16 +29,16 @@
     "params":{
       "dry_run":{
         "type":"boolean",
-        "description":"Perform a dry run but do not actually change any mappings",
+        "description":"Whether this request should only be a dry run rather than actually applying mappings",
         "default":false
       },
       "timeout":{
         "type":"time",
-        "description":"Specify timeout for acknowledging the cluster state update"
+        "description":"Period to wait for a response"
       },
       "master_timeout":{
         "type":"time",
-        "description":"Specify timeout for connection to master"
+        "description":"Period to wait for a connection to the master node"
       }
     },
     "body":{