Document changing columns.

schema.md

@@ -3,6 +3,7 @@
 - [Introduction](#introduction)
 - [Creating & Dropping Tables](#creating-and-dropping-tables)
 - [Adding Columns](#adding-columns)
+- [Changing Columns](#changing-columns)
 - [Renaming Columns](#renaming-columns)
 - [Dropping Columns](#dropping-columns)
 - [Checking Existence](#checking-existence)
@@ -68,7 +69,7 @@ Command | Description
 `$table->date('created_at');` | DATE equivalent to the table
 `$table->dateTime('created_at');` | DATETIME equivalent to the table
 `$table->decimal('amount', 5, 2);` | DECIMAL equivalent with a precision and scale
-`$table->double('column', 15, 8);` | DOUBLE equivalent with precision, 15 digits in total and 8 after the decimal point 
+`$table->double('column', 15, 8);` | DOUBLE equivalent with precision, 15 digits in total and 8 after the decimal point
 `$table->enum('choices', array('foo', 'bar'));` | ENUM equivalent to the table
 `$table->float('amount');` | FLOAT equivalent to the table
 `$table->increments('id');` | Incrementing ID to the table (primary key).
@@ -98,6 +99,23 @@ If you are using the MySQL database, you may use the `after` method to specify t
 
  $table->string('name')->after('email');
 
+<a name="changing-columns"></a>
+## Changing Columns
+
+Sometimes you may need to modify an existing column. For example, you may wish to increase the size of a string column. The `change` method makes it easy! For example, let's increase the size of the `name` column from 25 to 50:
+
+ Schema::table('users', function($table)
+ {
+  $table->string('name', 50)->change();
+ });
+
+We could also modify a column to be nullable:
+
+ Schema::table('users', function($table)
+ {
+  $table->string('name', 50)->nullable()->change();
+ });
+
 <a name="renaming-columns"></a>
 ## Renaming Columns