Merge pull request #5 from PostsSystem/features/instruct_for_add_new_conten

Описана процедура добавления контента

features/content/README.MD

@@ -0,0 +1,33 @@
+## How to create content?
+
+For example, you want to create content named "MyFormat". To do this, you must perform the following actions:
+
+1. Copy "template" folder from "core/features" in "core/features/content"
+2. Rename this folder in "myformat"
+3. Inside the "myformat" folder rename all the "template" on "content.myformat"
+4. In the "settings.gradle" file in the "includes" array add the following code:
+```kotlin
+    ":features:content:myformat:common",
+    ":features:content:myformat:client",
+    ":features:content:myformat:server",
+```
+5. In the "core/features/content/myformat/common/src" folder create folders with appropriate subfolders "commonMain/kotlin/dev/inmo/postssystem/features/content/myformat/common":
+6. In the last folder "сommon", create a data class and the configurator as shown below:
+```kotlin
+   @Serializable
+   data class MyFormatContent(
+       // Your code
+   ) : Content
+```
+
+```kotlin
+object MyFormatContentSerializerModuleConfigurator : ContentSerializersModuleConfigurator.Element {
+    override fun PolymorphicModuleBuilder<Content>.invoke() {
+        subclass(MyFormatContent::class, MyFormatContent.serializer())
+    }
+}
+```
+7. In two "di.kt" file located in "core/client/src/commonMain/kotlin/dev/inmo/postsystem/client" and "core/server/src/main/java/dev/inmo/postsystem/client" respectively add the following string:
+```kotlin
+    singleWithRandomQualifier<ContentSerializersModuleConfigurator.Element> { MyFormatContentSerializerModuleConfigurator }
+```