add docs for accessing the serializer/adapter directly
add docs for accessing the serializer/adapter directly

tricknotes/active-model-adapter,tricknotes/active-model-adapter,sly7-7/active-model-adapter,quaertym/active-model-adapter,bmac/active-model-adapter,Robdel12/active-model-adapter,Robdel12/active-model-adapter,fivetanley/active-model-adapter,jcope2013/active-model-adapter,sly7-7/active-model-adapter,sly7-7/active-model-adapter,blimmer/active-model-adapter,quaertym/active-model-adapter,blimmer/active-model-adapter,Robdel12/active-model-adapter,sly7-7/active-model-adapter,fivetanley/active-model-adapter,tricknotes/active-model-adapter,blimmer/active-model-adapter,ember-data/active-model-adapter,blimmer/active-model-adapter,bmac/active-model-adapter,tricknotes/active-model-adapter,jcope2013/active-model-adapter,Robdel12/active-model-adapter,bmac/active-model-adapter,jcope2013/active-model-adapter,jcope2013/active-model-adapter,ember-data/active-model-adapter,quaertym/active-model-adapter,fivetanley/active-model-adapter,fivetanley/active-model-adapter,quaertym/active-model-adapter,ember-data/active-model-adapter,bmac/active-model-adapter