Documentation of Single APK Approach Configuration (opensrp#1313)

* Create configuration.md

* Rename docs/configuration.md to docs/configurability/readme.md

* Update and rename app-configurability.md to bottom-nav-config.md

* Update readme.md

Co-authored-by: Benjamin Mwalimu <dubdabasoduba@gmail.com>
Co-authored-by: Peter Lubell-Doughtie <peter@ona.io>

Author: 3 people

docs/configurability/app-configurability.md docs/configurability/bottom-nav-config.md

@@ -1,7 +1,5 @@
 
-# App Configurability
-
-- #### Bottom Navigation Configuration
+#### Bottom Navigation Configuration
   - **Navigation Item**
   - **Action Configuration**
   - **Handle Navigation Action**
@@ -67,4 +65,4 @@ fun getJson(): Json {
     serializersModule = module
   }
 }
-```
+```