Add migrating to 8.0 guide

[Jack-Byrne]

Add information to highlight important integration updates. This guide includes updates to the accepted environments, configuration options, and HMI API updates integrators will need to take note of.

[jacobkeeler]

Should probably include a section for the behavior changes for the phone call event here:

OnEventChanged (PHONE_CALL)

The behavior of the PHONE_CALL event was changed to only affect the audioStreamingState of an app. Rather than automatically deactivating the active app, SDL Core will now only change the audioStreamingState of all apps to NOT_AUDIBLE when BC.OnEventChanged(PHONE_CALL, active=true) is sent, leaving each app's hmiLevel unchanged. This allows the HMI to start a phone call in the background without leaving the app screen, if desired.

The HMI can still control the hmiLevel of the app during a phone call event by sending BC.OnAppDeactivated(appID) and BC.OnAppActivated(appID) where appropriate.

[ShobhitAd]

We might want to also add a link to this guide in the overview page https://smartdevicelink.com/en/guides/core/overview/#migrating-to-newer-sdl-versions

[Jack-Byrne]

Done

[ShobhitAd]

Suggested change

	The parameters in the notification have also changed.
	The parameter `requestID` is used instead of appID to identify which specific request should have its timeout extended.
	The parameter `methodName` should include the interface name and the rpc. For example: `”TTS.Speak”`.
	The parameter `resetPeriod` allows the HMI to specify how long Core should delay the application request’s timeout.
	The parameters in the notification have also changed:
	- The parameter `requestID` is used instead of appID to identify which specific request should have its timeout extended.
	- The parameter `methodName` should include the interface name and the rpc. For example: `”TTS.Speak”`.
	- The parameter `resetPeriod` allows the HMI to specify how long Core should delay the application request’s timeout.

[theresalech]

@JackLivio please let me know if you have any questions about my feedback. Thanks!