Documentation for using Entity Share

[willguv]

Could be a useful option for sharing whole sections

Combine https://cumbria.localgov.blog/2022/05/31/using-entity-share-with-localgov-drupal/ with tweaks by Newcastle @Mjeffbrown

[nccchris]

Here's a patch file containing the current change that we need to get entity_share to work as expected. This needs to be applied to the site that's the client side of the entity share setup.
jsonapi.txt