Added some docs

lib.daggerscopes/src/main/java/com/gpeal/droidconanvilsample/lib/daggerscopes/ContributesApi.kt

@@ -1,12 +1,14 @@
 package com.gpeal.droidconanvilsample.lib.daggerscopes
 
 /**
- * Adds api to the @AppComponent graph. Equivalent to the following declaration in an application module:
+ * Annotate a retrofit interface with this to automatically contribute it to the [AppScope] graph.
+ * Equivalent to the following declaration in an application module:
  *
  *     @Provides
  *     @Reusable
  *     public fun provideYourApi(retrofit: Retrofit): YourApi = retrofit.create(YourApi::class.java)
  *
+ * The generated code created via the :anvilcodegen module.
  */
 @Target(AnnotationTarget.CLASS)
 annotation class ContributesApi

lib.daggerscopes/src/main/java/com/gpeal/droidconanvilsample/lib/daggerscopes/SingleIn.kt

@@ -3,7 +3,32 @@ package com.gpeal.droidconanvilsample.lib.daggerscopes
 import javax.inject.Scope
 import kotlin.reflect.KClass
 
-// This could live in a shared library module.
+/**
+ * This annotation lets you use the same annotation to represent which scope you want to contribute an Anvil object to
+ * and also as `@SingleIn(YourScope::class)`.
+ *
+ * Without `@SingleIn`, an AppComponent contribution might look like this:
+ * ```
+ * @Singleton
+ * @ContributesBinding(AppScope::class)
+ * class YourClassImpl : YourClass
+ * ```
+ * Singleton is a well defined pattern for AppScope but the scope naming becomes more confusing once you start defining your
+ * own components.
+ * `@SingleIn` prevents you from memorizing two names per component. The above example becomes:
+ * ```
+ * @SingleIn(AppScope::class)
+ * @ContributesBinding(AppScope::class)
+ * class YourClassImpl : YourClass
+ * ```
+ *
+ * And custom components would look like:
+ * ```
+ * @SingleIn(YourScope::class)
+ * @ContributesBinding(YourScope::class)
+ * class YourClassImpl : YourClass
+ * ```
+ */
 @Scope
 @Retention(AnnotationRetention.RUNTIME)
 annotation class SingleIn(val clazz: KClass<*>)