update README and add contribution policy

Author: Bulat Shakirzyanov

CONTRIBUTING.md

@@ -0,0 +1,20 @@
+# Contributing
+
+## Reporting bugs
+
+It is inevitable that code will have bugs. There are a few things you can do to
+help the maintainer to fix the bug that you've discovered quicker:
+
+* [Use the PHP Driver Jira](https://datastax-oss.atlassian.net/projects/PHP) to report all issues and bugs.
+* Include the version of the Driver, PHP and Cassandra or DSE in your Jira ticket.
+* Include a complete stack trace of the failure as well as any available logs.
+* Include any additional information you think is relevant - the description of
+  your setup, any non-default Driver configuration, etc.
+* Write a failing test. The PHP Driver uses [PHPUnit test framework](https://phpunit.de/). A reliably
+  failing test is the fastest way to demonstrate and fix a problem.
+
+## Pull Requests
+
+If you're able to fix a bug yourself, you can [fork the repository](https://help.github.com/articles/fork-a-repo/) and [submit a pull request](https://help.github.com/articles/using-pull-requests/) with the fix.
+
+To protect DataStax and the community, all contributors are required to [sign the DataStax Contribution License Agreement](http://cla.datastax.com/). The process is completely electronic and should only take a few minutes.

README.md

@@ -63,7 +63,12 @@ __NOTE__: Apache Cassandra 2.1 support is limited to the Cassandra 2.0 API, e.g.
 
 __NOTE__: Windows support is planned for a later, more stable release.
 
-## What's new in v1.0.0.alpha
+## Status of v1.0.0.alpha
+
+The current release is an early alpha. This means that it lacks some features
+and stability, but should be enough to start testing and working with Apache
+Cassandra. Below, you'll find a list of functionality that is already supported
+as well as what's plan for the upcoming releases.
 
 Features:
 
@@ -74,6 +79,16 @@ Features:
 * [SSL encryption](feature/ssl_encryption.feature).
 * [Credentials authentication](src/Cassandra/Cluster/Builder.php#L312-L320).
 
+Planned:
+
+* Windows support.
+* Expose [Schema Metadata](http://datastax.github.io/cpp-driver/api/struct_cass_session/#1afc51badec695483e4cde43ae0fc1e876).
+* Add arithmetic functions to numeric types.
+
+## Contributing
+
+[Read our contribution policy](CONTRIBUTING.md) for a detailed description of the process.
+
 ## Code examples
 
 The DataStax PHP Driver uses the amazing [Behat Framework](http://docs.behat.org/)