Add changes_count to the merge requests API

This returns the `real_size` of the MR's diff, which is a string indicating the
number of changes. If the diff overflows after _n_ files, the string will be
`$n+`.

1 files changed, 21 insertions, 1 deletions

diff --git a/doc/api/merge_requests.md b/doc/api/merge_requests.md
index 50a971102fb..6de460f2778 100644
--- a/doc/api/merge_requests.md
+++ b/doc/api/merge_requests.md
@@ -15,6 +15,11 @@ given state (`opened`, `closed`, or `merged`) or all of them (`all`).
 The pagination parameters `page` and `per_page` can be used to
 restrict the list of merge requests.
 
+**Note**: the `changes_count` value in the response is a string, not an
+integer. This is because when an MR has too many changes to display and store,
+it will be capped at 1,000. In that case, the API will return the string
+`"1000+"` for the changes count.
+
 ```
 GET /merge_requests
 GET /merge_requests?state=opened
@@ -92,6 +97,7 @@ Parameters:
     "sha": "8888888888888888888888888888888888888888",
     "merge_commit_sha": null,
     "user_notes_count": 1,
+    "changes_count": "1",
     "should_remove_source_branch": true,
     "force_remove_source_branch": false,
     "web_url": "http://example.com/example/example/merge_requests/1",
@@ -130,6 +136,11 @@ will be the same. In the case of a merge request from a fork,
 `target_project_id` and `project_id` will be the same and
 `source_project_id` will be the fork project's ID.
 
+**Note**: the `changes_count` value in the response is a string, not an
+integer. This is because when an MR has too many changes to display and store,
+it will be capped at 1,000. In that case, the API will return the string
+`"1000+"` for the changes count.
+
 Parameters:
 
 | Attribute           | Type           | Required | Description                                                                                                                    |
@@ -198,6 +209,7 @@ Parameters:
     "sha": "8888888888888888888888888888888888888888",
     "merge_commit_sha": null,
     "user_notes_count": 1,
+    "changes_count": "1",
     "should_remove_source_branch": true,
     "force_remove_source_branch": false,
     "web_url": "http://example.com/example/example/merge_requests/1",
@@ -274,6 +286,7 @@ Parameters:
   "sha": "8888888888888888888888888888888888888888",
   "merge_commit_sha": "9999999999999999999999999999999999999999",
   "user_notes_count": 1,
+  "changes_count": "1",
   "should_remove_source_branch": true,
   "force_remove_source_branch": false,
   "web_url": "http://example.com/example/example/merge_requests/1",
@@ -386,6 +399,7 @@ Parameters:
   "sha": "8888888888888888888888888888888888888888",
   "merge_commit_sha": null,
   "user_notes_count": 1,
+  "changes_count": "1",
   "should_remove_source_branch": true,
   "force_remove_source_branch": false,
   "web_url": "http://example.com/example/example/merge_requests/1",
@@ -480,6 +494,7 @@ POST /projects/:id/merge_requests
   "sha": "8888888888888888888888888888888888888888",
   "merge_commit_sha": null,
   "user_notes_count": 0,
+  "changes_count": "1",
   "should_remove_source_branch": true,
   "force_remove_source_branch": false,
   "web_url": "http://example.com/example/example/merge_requests/1",
@@ -565,6 +580,7 @@ Must include at least one non-required attribute from above.
   "sha": "8888888888888888888888888888888888888888",
   "merge_commit_sha": null,
   "user_notes_count": 1,
+  "changes_count": "1",
   "should_remove_source_branch": true,
   "force_remove_source_branch": false,
   "web_url": "http://example.com/example/example/merge_requests/1",
@@ -670,6 +686,7 @@ Parameters:
   "sha": "8888888888888888888888888888888888888888",
   "merge_commit_sha": "9999999999999999999999999999999999999999",
   "user_notes_count": 1,
+  "changes_count": "1",
   "should_remove_source_branch": true,
   "force_remove_source_branch": false,
   "web_url": "http://example.com/example/example/merge_requests/1",
@@ -747,6 +764,7 @@ Parameters:
   "sha": "8888888888888888888888888888888888888888",
   "merge_commit_sha": null,
   "user_notes_count": 1,
+  "changes_count": "1",
   "should_remove_source_branch": true,
   "force_remove_source_branch": false,
   "web_url": "http://example.com/example/example/merge_requests/1",
@@ -822,7 +840,8 @@ Example response when the GitLab issue tracker is used:
       "created_at" : "2016-01-04T15:31:51.081Z",
       "iid" : 6,
       "labels" : [],
-      "user_notes_count": 1
+      "user_notes_count": 1,
+      "changes_count": "1"
    },
 ]
 ```
@@ -1077,6 +1096,7 @@ Example response:
     "sha": "8888888888888888888888888888888888888888",
     "merge_commit_sha": null,
     "user_notes_count": 7,
+    "changes_count": "1",
     "should_remove_source_branch": true,
     "force_remove_source_branch": false,
     "web_url": "http://example.com/example/example/merge_requests/1"