added info to readme about using parameter order with define()

Author: garrettw

README.md

@@ -257,6 +257,10 @@ $myObj = $injector->make('MyClass');
 var_dump($myObj instanceof MyClass); // true
 ```
 
+> **NOTE:** Since this `define()` call is passing raw values (as evidenced by the colon `:` usage),
+you can achieve the same result by omitting the array key(s) and relying on parameter order rather
+than name. Like so: `$injector->define('MyClass', [$dependencyInstance]);`
+
 ###### Specifying Injection Definitions On the Fly
 
 You may also specify injection definitions at call-time with `Auryn\Injector::make`. Consider:
@@ -329,12 +333,12 @@ on type-hints, class name definitions and existing instances. But what happens i
 a scalar or other non-object variable into a class? First, let's establish the following behavioral
 rule:
 
-> **IMPORTANT:** The Injector assumes all injection definitions are class names by default.
+> **IMPORTANT:** The Injector assumes all named-parameter definitions are class names by default.
 
-If you want the Injector to treat a parameter definition as a "raw" value and not a class name, you
-must prefix the parameter name in your definition with a colon character `:`. For example, consider
-the following code in which we tell the Injector to share a `PDO` database connection instance and
-define its scalar constructor parameters:
+If you want the Injector to treat a named-parameter definition as a "raw" value and not a class name,
+you must prefix the parameter name in your definition with a colon character `:`. For example,
+consider the following code in which we tell the Injector to share a `PDO` database connection
+instance and define its scalar constructor parameters:
 
 ```php
 <?php
@@ -356,6 +360,12 @@ easily specified arrays or integers or any other data type in the above definiti
 parameter name is prefixed with a `:`, Auryn will inject the value directly without attempting to
 instantiate it.
 
+> **NOTE:** As mentioned previously, since this `define()` call is passing raw values, you may opt to
+assign the values by parameter order rather than name. Since PDO's first three parameters are `$dsn`,
+`$username`, and `$password`, in that order, you could accomplish the same result by leaving out the
+array keys, like so:
+`$injector->define('PDO', ['mysql:dbname=testdb;host=127.0.0.1', 'dbuser', 'dbpass']);`
+
 ### Global Parameter Definitions
 
 Sometimes applications may reuse the same value everywhere. However, it can be a hassle to manually