Fix some grammar in the API docs

doc/api/commits.md

@@ -12,8 +12,8 @@ GET /projects/:id/repository/commits
 | --------- | ---- | -------- | ----------- |
 | `id`      | integer/string | yes | The ID of a project or NAMESPACE/PROJECT_NAME owned by the authenticated user
 | `ref_name` | string | no | The name of a repository branch or tag or if not given the default branch |
-| `since` | string | no | Only commits after or in this date will be returned in ISO 8601 format YYYY-MM-DDTHH:MM:SSZ |
-| `until` | string | no | Only commits before or in this date will be returned in ISO 8601 format YYYY-MM-DDTHH:MM:SSZ |
+| `since` | string | no | Only commits after or on this date will be returned in ISO 8601 format YYYY-MM-DDTHH:MM:SSZ |
+| `until` | string | no | Only commits before or on this date will be returned in ISO 8601 format YYYY-MM-DDTHH:MM:SSZ |
 ```bash
 curl --header "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" "https://gitlab.example.com/api/v3/projects/5/repository/commits"

doc/api/deploy_keys.md

@@ -137,7 +137,7 @@ Example response:
 ## Delete deploy key
-Removes a deploy key from the project. If the deploy is used only for this project, it will be deleted from the system.
+Removes a deploy key from the project. If the deploy key is used only for this project, it will be deleted from the system.
 ```
 DELETE /projects/:id/deploy_keys/:key_id

lib/api/commits.rb

@@ -16,8 +16,8 @@ module API
       end
       params do
         optional :ref_name, type: String, desc: 'The name of a repository branch or tag, if not given the default branch is used'
-        optional :since,    type: DateTime, desc: 'Only commits after or in this date will be returned'
-        optional :until,    type: DateTime, desc: 'Only commits before or in this date will be returned'
+        optional :since,    type: DateTime, desc: 'Only commits after or on this date will be returned'
+        optional :until,    type: DateTime, desc: 'Only commits before or on this date will be returned'
         optional :page,     type: Integer, default: 0, desc: 'The page for pagination'
         optional :per_page, type: Integer, default: 20, desc: 'The number of results per page'
         optional :path,     type: String, desc: 'The file path'