Fix headings

README.md

@@ -1,9 +1,7 @@
 # Asynchronous Server App Boilerplate
 
 [![image](https://travis-ci.com/TeskaLabs/asab.svg?branch=master)](https://travis-ci.com/TeskaLabs/asab)
-
 [![image](https://img.shields.io/github/license/TeskaLabs/asab)](https://github.com/TeskaLabs/asab/blob/master/LICENSE)
-
 [![image](https://readthedocs.org/projects/asab/badge/?version=latest)](https://asab.readthedocs.io/en/latest/?badge=latest)
 
 Read the documentation on [Readthedocs](http://asab.readthedocs.io/)
@@ -17,7 +15,7 @@ non-blocking, speedy and hence scalable.
 We make every effort to build ASAB container-friendly so that you can deploy
 ASAB-based microservice via Docker or Kubernetes in a breeze.
 
-** Contributions are welcome! **
+**Contributions are welcome!**
 
 ASAB is an open-source software, available under BSD 3-Clause License. It is currently maintained by [TeskaLabs Ltd](https://www.teskalabs.com).
 It means that anyone is freely licensed to use, copy, study, and change the software in any way,
@@ -101,21 +99,17 @@ The REST API is automatically documented using OpenAPI3 standard and the Swagger
 Principles
 ----------
 
--   Write once, use many times
--   Keep it simple
--   Well [documented](http://asab.readthedocs.io/)
--   Asynchronous via Python 3 `async`/`await` and `asyncio`
--   [Event-driven
-	Architecture](https://en.wikipedia.org/wiki/Event-driven_architecture)
-	/ [Reactor pattern](https://en.wikipedia.org/wiki/Reactor_pattern)
--   Single-threaded core but compatible with threads
--   First-class support for
-	[containerization](https://en.wikipedia.org/wiki/Operating-system-level_virtualization)
--   Compatible with [pypy](http://pypy.org), Just-In-Time Python
-	compiler
--   Kappa architecture
--   Support for introspection
--   Modularized
+- Write once, use many times.
+- Keep it simple!
+- Well [documented](http://asab.readthedocs.io/).
+- Asynchronous with `asyncio` and `aiohttp` libraries.
+- [Event-driven Architecture](https://en.wikipedia.org/wiki/Event-driven_architecture) / [Reactor pattern](https://en.wikipedia.org/wiki/Reactor_pattern)
+- Single-threaded core but compatible with threads.
+- First-class support for [containerization](https://en.wikipedia.org/wiki/Operating-system-level_virtualization).
+- Compatible with [pypy](http://pypy.org), Just-In-Time Python compiler.
+- Kappa architecture
+- Support for introspection
+- Modularized
 
 ### Video tutorial