Provide documentation and update hook for removal of geolocation_googlegeocoder widget

Problem/Motivation

The geolocation_googlegeocoder plugin widget was removed in the transition to version 4. This prevents update hooks from running when moving from 3x -> 4x. Need to provide documentation/workflow on the correct way to migrate.

Steps to reproduce

1. Install version 3.x of module
2. use the GeolocationGoogleWidget (geolocation_googlegeocoder) field widget
3. Geocode several addresses
4. Install version 4.x of module
5. Run update hook
6. Error

The "geolocation_googlegeocoder" plugin does not exist

Proposed resolution

provide direction on transition from 3.x to 4.x or an update hook to transition for end user.