Fix grammar and punctuation (mdn#18449)

Author: de-oz

files/en-us/web/api/webvr_api/index.md

@@ -68,13 +68,13 @@ Many WebVR hardware setups feature controllers that go along with the headset. T
 - {{DOMxRef("VRDisplay")}}
   - : Represents any VR device supported by this API. It includes generic information such as device IDs and descriptions, as well as methods for starting to present a VR scene, retrieving eye parameters and display capabilities, and other important functionality.
 - {{DOMxRef("VRDisplayCapabilities")}}
-  - : Describes the capabilities of a {{DOMxRef("VRDisplay")}} — it's features can be used to perform VR device capability tests, for example can it return position information.
+  - : Describes the capabilities of a {{DOMxRef("VRDisplay")}} — its features can be used to perform VR device capability tests, for example can it return position information.
 - {{DOMxRef("VRDisplayEvent")}}
   - : Represents the event object of WebVR-related events (see the [window object extensions](#window) listed below).
 - {{DOMxRef("VRFrameData")}}
   - : Represents all the information needed to render a single frame of a VR scene; constructed by {{DOMxRef("VRDisplay.getFrameData()")}}.
 - {{DOMxRef("VRPose")}}
-  - : Represents the position state at a given timestamp (which includes orientation, position, velocity, and acceleration.)
+  - : Represents the position state at a given timestamp (which includes orientation, position, velocity, and acceleration).
 - {{DOMxRef("VREyeParameters")}}
   - : Provides access to all the information required to correctly render a scene for each given eye, including field of view information.
 - {{DOMxRef("VRFieldOfView")}}