Update docs for 0.2

Author: jmikola

docs/index.md

@@ -30,7 +30,7 @@ The preferred method of installing this library is with
 [Composer](https://getcomposer.org/) by running the following from your project
 root:
 
-    $ composer require "mongodb/mongodb=0.2.x-dev"
+    $ composer require "mongodb/mongodb=^0.2.0"
 
 ## Generated API Docs
 

docs/usage.md

@@ -1,20 +1,33 @@
 # Usage
 
+## Client class
+
+`MongoDB\Client` serves as an entry point for the library and driver. It is
+constructed with the same arguments as the driver's `MongoDB\Driver\Manager`
+class, which it composes. The Client class provides methods for creating a
+Database or Collection class (from the internal manager instance), as well as
+top-level operations, such as enumerating and dropping databases.
+
 ## Collection class
 
 `MongoDB\Collection` is perhaps the most useful class in this library. It
 provides methods for common operations on a collection, such as inserting
 documents, querying, updating, counting, etc.
 
-Constructing a `MongoDB\Collection` requires a `MongoDB\Manager` and a namespace
-for the collection. A [MongoDB namespace](http://docs.mongodb.org/manual/faq/developers/#faq-dev-namespace)
+Constructing a `MongoDB\Collection` requires a `MongoDB\Driver\Manager` and a
+namespace for the collection. A [MongoDB namespace](http://docs.mongodb.org/manual/faq/developers/#faq-dev-namespace)
 consists of a database name and collection name joined by a dot. `examples.zips`
-is on example of a namespace. A [write concern](http://docs.mongodb.org/manual/core/write-concern/)
+is one example of a namespace. Through normal use of the library, a Collection
+will typically be created via the `selectCollection()` method on the Manager or
+Database classes.
+
+A [write concern](http://docs.mongodb.org/manual/core/write-concern/)
 and [read preference](http://docs.mongodb.org/manual/core/read-preference/) may
-also be provided when constructing a Collection (if omitted, the Collection will
-use the Manager's values as its defaults).
+also be provided when constructing a Collection. If these options are omitted,
+the Collection will inherit them from the parent through which it was selected,
+or the Manager.
 
-## Finding a specific document
+### Finding a specific document
 
 ```
 <?php
@@ -51,3 +64,14 @@ array(5) {
   string(2) "CA"
 }
 ```
+
+## Database class
+
+`MongoDB\Database` provides methods for common operations on a database, such
+as creating, enumerating, and dropping collections.
+
+A [write concern](http://docs.mongodb.org/manual/core/write-concern/)
+and [read preference](http://docs.mongodb.org/manual/core/read-preference/) may
+also be provided when constructing a Database. If these options are omitted,
+the Database will inherit them from the Client through which it was selected,
+or the Manager.