Added motivation

README.md

@@ -1,7 +1,7 @@
 # grimoire
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-Grimoire is a database access layer inspired by Ecto's changeset system. It features flexible query API and builtin validation. It currently supports MySQL, PostgreSQL and SQLite3 but a custom adapter can be implemented easily using the Adapter interface.
+Grimoire is a database access layer inspired by Ecto. It features a flexible query API and built-in validation. It currently supports MySQL, PostgreSQL, and SQLite3 but a custom adapter can be implemented easily using the Adapter interface.
 
 Features:
 
@@ -13,6 +13,10 @@ Features:
 - Multi adapter support
 - Logger
 
+## Motivation
+
+Common go ORM accepts struct as a value for modifying records which has a problem of unable to differentiate between an empty, nil, or undefined value. It's a tricky problem especially when you want to have an endpoint that supports partial updates. Grimoire attempts to solve that problem by integrating Changeset system inspired from Elixir's Ecto. Changeset is a form like entity which allows us to not only solve that problem but also help us with casting, validations, and constraints check.
+
 ## Install
 
 ```bash