Add: note re: gin index for jsonb (#535)

* Add: note re: gin index for jsonb

* Small edits to note on adding gin index

Co-authored-by: Hiren Mistry <hiren.mistry@chai-monsters.com>

README.md

@@ -59,6 +59,7 @@ an "image" attachment on a `photos` table this would be an `image_data` column:
 ```
 $ rails generate migration add_image_data_to_photos image_data:text # or :jsonb
 ```
+If using `jsonb` consider adding a [gin index] for fast key-value pair searchability within `image_data`.
 
 Now create an uploader class (which you can put in `app/uploaders`) and
 register the attachment on your model:
@@ -175,3 +176,4 @@ The gem is available as open source under the terms of the [MIT License].
 [CoC]: /CODE_OF_CONDUCT.md
 [MIT License]: /LICENSE.txt
 [Contributing]: https://github.com/shrinerb/shrine/blob/master/CONTRIBUTING.md
+[gin index]: https://www.postgresql.org/docs/current/datatype-json.html#JSON-INDEXING

doc/getting_started.md

@@ -37,22 +37,26 @@ will use to store all information about the attachment:
 ```rb
 Sequel.migration do
   change do
-    add_column :photos, :image_data, :text # or :jsonb
+    add_column :photos, :image_data, :text # or :jsonb   
   end
 end
 ```
+
 <!--ActiveRecord-->
 ```rb
 class AddImageDataToPhotos < ActiveRecord::Migration
   def change
-    add_column :photos, :image_data, :text # or :jsonb
+    add_column :photos, :image_data, :text # or :jsonb   
   end
 end
 ```
+
 <!--Rails-->
-```
+```rb
 $ rails generate migration add_image_data_to_photos image_data:text  # or image_data:jsonb 
 ```
+If using `jsonb` consider adding a [gin index] for fast key-value pair searchability within `image_data`.
+
 <!--END_DOCUSAURUS_CODE_TABS-->
 
 Now you can create an uploader class for the type of files you want to upload,
@@ -1108,3 +1112,4 @@ Shrine.logger.level = Logger::WARN
 [storages]: https://shrinerb.com/docs/external/extensions#storages
 [plugins]: https://shrinerb.com/plugins
 [external plugins]: https://shrinerb.com/docs/external/extensions#plugins
+[gin index]: https://www.postgresql.org/docs/current/datatype-json.html#JSON-INDEXING