Adding API page

It's not in the YML, meaning it's not built by the docs system

Author: iriark01

mkdocs.yml

@@ -5,6 +5,7 @@ docs_dir: docs
 pages:
 - ['index.md','uVisor Documentation']
 - ['api/QUICKSTART.md', 'uVisor', 'Quick start guide']
+- ['api/API.md', 'uVisor', 'API documentation']
 - ['core/DEVELOPING_LOCALLY.md', 'uVisor', 'Developing Locally']
 - ['api/DEBUGGING.md', 'uVisor', 'Debugging uVisor']
 - ['core/PORTING.md', 'Porting uVisor', 'Porting uVisor']