Added the initial FAQ section

docs/faq.md

@@ -0,0 +1,29 @@
+# FAQ
+
+## Why lifecycle callbacks are not called on iOS (or any other non-Android platform)?
+
+On non-Android platforms the `Lifecycle` should usually be controlled manually. This can be done by creating an instance of `LifecycleRegistry`, passing it to `DefaultComponentContext`, and then controlling the `LifecycleRegistry` based on platform-specific lifecycle events. Please refer to the sample project to learn about platform integrations.
+
+However, there are convenient APIs for some platforms.
+
+### Lifecycle on iOS
+
+If the root component lives in the application scope (i.e. Decompose is used in the entire application, not partially in one screen), then `ApplicationLifecycle` API from Essenty can be used (since Essenty version `2.0.0-alpha07`). Prior to that Essenty version, `ApplicationLifecycle` had been provided by Decompose.
+
+### Lifecycle on Compose for Desktop (JVM)
+
+There is the `LifecycleController` API available on Compose for Desktop.
+
+## Error "Another supplier is already registered with the key"
+
+This exception is thrown by `StateKeeper` when its `register` method is called second time with the same key.
+
+- If you are using Compose, make sure that you create the root component context and component outside Compose. See the [docs](component/overview/#root-componentcontext). Otherwise, a second instance can be created if the root Composable function re-composes.
+- If you are using more than one `childStack` in one component (or more than one navigation model of the same kind in one component), then please supply the `key` argument for every such function.
+
+## Error "Configurations must be unique"
+
+This exception is thrown when duplicated component configurations are detected by a navigation model (e.g. Child Stack). Duplicates are checked according to the `equals` method, which all configurations must be properly implementing. See the [docs](navigation/overview/#component-configurations-and-child-factories) for more information.
+
+- Prefer `pushNew` function instead of `push` when showing a component on a button click, it will properly handle accidental double clicks.
+- Prefer `pushToFront` to prevent duplicated components with the same data (configurations) in the stack.

mkdocs.yml

@@ -61,6 +61,7 @@ nav:
     - Calling Composable functions with ViewModels: tips-tricks/composable-viewmodel.md
     - Hosting a component in navigation-compose: tips-tricks/navigation-compose-component.md
 
+  - FAQ: faq.md
   - Community: community.md
 
   # Configuration