add an intro to the migration guide

Author: aallam

README.md

@@ -59,7 +59,7 @@ Install the Kotlin client by adding the following dependency to your `gradle.bui
 For full documentation, visit the **[Algolia Kotlin API Client](https://www.algolia.com/doc/api-client/getting-started/install/kotlin/)**.
 
 ⚠️ Important: starting from version `1.4.0` the library is compatible only with kotlin version `1.3.70` or higher; for previous versions of kotlin, please use version `1.3.1` of the library.  
-ℹ️ If you migrate from `1.4.0` to `1.5.0` please follow the [migration guide](guide/Migrate_1.4.x_1.5.x.md).
+ℹ️ Please follow the [migration guide](docs/guide/Migrate_1.4.x_1.5.x.md) to migrate from `1.4.x` or below to the latest version.
 
 ### Coroutines
 

guide/Migrate_1.4.x_1.5.x.md renamed to docs/guide/Migrate_1.4.x_1.5.x.md

@@ -1,6 +1,9 @@
 # Migrate from 1.4.x to 1.5.x
 
-## Gradle
+Version `1.5.x` of the library uses the latest Kotlin version `1.4.0` and Kotlin serialization `1.0.0`. If you want to migrate from 
+`1.4.x` to `1.5.x` please follow these steps:
+
+### Gradle
 The library now uses the full power of [Gradle metadata module](https://blog.gradle.org/gradle-metadata-1.0).
 
 In the case you are using the android variant of the library 
@@ -15,7 +18,7 @@ implementation "com.algolia:algoliasearch-client-kotlin:$kotlin_client_version"
 ```
 Otherwise, nothing has to be changed.
 
-## Serialization
+### Serialization
 A significant part of the public API was renamed or extracted to a separate package.
 Here is the most important parts from the kotlinx serialization's [migration guide](https://github.com/Kotlin/kotlinx.serialization/blob/1.0.0-RC/docs/migration.md):