Tidied up the filters agg docs and added a coming[] tag

docs/reference/search/aggregations/bucket/filters-aggregation.asciidoc

@@ -1,113 +1,130 @@
 [[search-aggregations-bucket-filters-aggregation]]
 === Filters
 
-Defines a multi bucket aggregations where each bucket is associated with a filter. Each bucket will collect all
-documents that match its associated filter.
+coming[1.4.0]
+
+Defines a multi bucket aggregations where each bucket is associated with a
+filter. Each bucket will collect all documents that match its associated
+filter.
 
 Example:
 
 [source,js]
 --------------------------------------------------
 {
-    "aggs" : {
-        "messages" : {
-            "filters" : {
-                "filters" : {
-                    "errors" : { "query" : { "match" : { "body" : "error" } } },
-                    "warnings" : { "query" : { "match" : { "body" : "warning" } } }
-                }
-            },
-            "aggs" : { "monthly" : { "histogram" : { "field" : "timestamp", "interval" : "1M" } } }
+  "aggs" : {
+    "messages" : {
+      "filters" : {
+        "filters" : {
+          "errors" :   { "term" : { "body" : "error"   }},
+          "warnings" : { "term" : { "body" : "warning" }}
+        }
+      },
+      "aggs" : {
+        "monthly" : {
+          "histogram" : {
+            "field" : "timestamp",
+            "interval" : "1M"
+          }
         }
+      }
     }
+  }
 }
 --------------------------------------------------
 
-In the above example, we analyze log messages. The aggregation will build two collection (buckets) of log messages - one
-for all those containing an error, and another for all those containing a warning. And for each of these buckets it will
-break them down by month.
+In the above example, we analyze log messages. The aggregation will build two
+collection (buckets) of log messages - one for all those containing an error,
+and another for all those containing a warning. And for each of these buckets
+it will break them down by month.
 
 Response:
 
 [source,js]
 --------------------------------------------------
-{
-    ...
-
-    "aggs" : {
-        "messages" : {
-            "buckets" : {
-                "errors" : {
-                    "doc_count" : 34,
-                    "monthly" : {
-                        "buckets : [
-                            ... // the histogram monthly breakdown
-                        ]
-                    }
-                },
-                "warnings" : {
-                    "doc_count" : 439,
-                    "monthly" : {
-                        "buckets : [
-                            ... // the histogram monthly breakdown
-                        ]
-                    }
-                }
+...
+  "aggs" : {
+    "messages" : {
+      "buckets" : {
+        "errors" : {
+          "doc_count" : 34,
+            "monthly" : {
+              "buckets : [
+                ... // the histogram monthly breakdown
+              ]
+            }
+          },
+          "warnings" : {
+            "doc_count" : 439,
+            "monthly" : {
+              "buckets : [
+                 ... // the histogram monthly breakdown
+              ]
             }
+          }
         }
+      }
     }
-}
+  }
+...
 --------------------------------------------------
 
 ==== Anonymous filters
 
-The filters field can also be provided as an array of filters, as in the following request:
+The filters field can also be provided as an array of filters, as in the
+following request:
 
 [source,js]
 --------------------------------------------------
 {
-    "aggs" : {
-        "messages" : {
-            "filters" : {
-                "filters" : [
-                    "query" : { "match" : { "body" : "error" } },
-                    "query" : { "match" : { "body" : "warning" } }
-                ]
-            },
-            "aggs" : { "monthly" : { "histogram" : { "field" : "timestamp", "interval" : "1M" } } }
+  "aggs" : {
+    "messages" : {
+      "filters" : {
+        "filters" : [
+          { "term" : { "body" : "error"   }},
+          { "term" : { "body" : "warning" }}
+        ]
+      },
+      "aggs" : {
+        "monthly" : {
+          "histogram" : {
+            "field" : "timestamp",
+            "interval" : "1M"
+          }
         }
+      }
     }
+  }
 }
 --------------------------------------------------
 
-The filtered buckets are returned in the same order as provided in the request.  The response for this example would be:
+The filtered buckets are returned in the same order as provided in the
+request.  The response for this example would be:
 
 [source,js]
 --------------------------------------------------
-{
-    ...
-
-    "aggs" : {
-        "messages" : {
-            "buckets" : [
-                {
-                    "doc_count" : 34,
-                    "monthly" : {
-                        "buckets : [
-                            ... // the histogram monthly breakdown
-                        ]
-                    }
-                },
-                {
-                    "doc_count" : 439,
-                    "monthly" : {
-                        "buckets : [
-                            ... // the histogram monthly breakdown
-                        ]
-                    }
-                }
+...
+  "aggs" : {
+    "messages" : {
+      "buckets" : [
+        {
+          "doc_count" : 34,
+          "monthly" : {
+            "buckets : [
+              ... // the histogram monthly breakdown
             ]
+          }
+        },
+        {
+          "doc_count" : 439,
+          "monthly" : {
+            "buckets : [
+              ... // the histogram monthly breakdown
+            ]
+          }
         }
+      ]
     }
-}
+  }
+...
 --------------------------------------------------