Add Changes section (#125)

This section summarizes substantial changes and notable editorial
improvements to guide review.

Co-authored-by: Reilly Grant <[email protected]>

index.bs

@@ -913,3 +913,38 @@ urlPrefix: https://html.spec.whatwg.org/multipage/
     }
 }
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+Changes {#changes}
+===========
+
+This section summarizes substantial changes and notable editorial improvements to guide review. Full details are available from the <a href="https://github.com/w3c/deviceorientation/commits/main">commit log</a>. Changes since the <a href="https://www.w3.org/TR/2016/CR-orientation-event-20160818/">Candidate Recommendation 2016-08-18</a>:
+
+- Add Permissions Policy integration
+- Add note to implementers about bundling permission requests
+- Export powerful features Accelerometer, Gyroscope and Magnetometer
+- Add Permissions API integration, start requiring requestPermission() usage
+- editorial: Define API section more normatively and with more dfns
+- editorial: Reorder acceleration explanation in Device Motion Model section
+- editorial: Update explanations of the device rotation and motion references
+- editorial: Use more precise event handling terms, modernize others
+- editorial: Refer to [[SCREEN-ORIENTATION]] instead of the orientation change event
+- editorial: Reword requirements in "Security and privacy considerations"
+- Mark use cases and requirements and examples sections non-normative
+- Remove the oncompassneedscalibration event
+- Update references to "triggered by user activation", now referred to as "transient activation"
+- Align with DOM phrasing on firing events
+- Add a note about acceleration properties for DeviceMotionEvent
+- Add a note explaining how the coordinate system differs from the CSS coordinate system
+- Require no more precise than 0.1 degrees, 0.1 degrees per second, 0.1 meters per second squared to mitigate a <a href="https://github.com/w3c/deviceorientation/issues/85">passive fingerprinting issue</a>
+- Update constructor definition in IDL with the Web IDL
+- Add explicit [Exposed] to interfaces
+- Update IDL dictionaries with new dictionary defaulting setup
+- Note the deviceorientationabsolute event and its ondeviceorientationabsolute event handler IDL attribute have limited implementation experience
+- Add requestPermission() API static operation to both DeviceOrientationEvent and DeviceMotionEvent
+- Add [SecureContext] to event handlers ondeviceorientation, ondevicemotion and ondeviceorientationabsolute
+- Restrict all interfaces to secure contexts
+- Remove [NoInterfaceObject] from DeviceAcceleration and DeviceRotationRate
+- Make security and privacy considerations normative
+- Add the ondeviceorientationabsolute event handler attribute into the IDL block (was only in prose)
+- Remove '?' from dictionary members of DeviceMotionEventInit
+- Use [Exposed=Window] extended attribute