Doc change: Adjust security sandbox description.

e-mails), reading or writing another application's files, performing

network access, keeping the device awake, etc.<p>

<p>An application's process is a secure sandbox.  It can't disrupt other

applications, except by explicitly declaring the <em>permissions</em> it needs

for additional capabilities not provided by the basic sandbox.  These

permissions it requests can be handled by the operating in various ways,

typically by automatically allowing or disallowing based on certificates or

by prompting the user.  The permissions required by an application are declared

statically in that application, so they can be known up-front at install time

and will not change after that.</p>

<p>An application's process runs in a security sandbox. The sandbox is designed

to prevent applications from disrupting each other, except by explicitly

declaring the <em>permissions</em> they need for additional capabilities not

provided by the basic sandbox. The system handles requests for permissions

in various ways, typically by automatically allowing or disallowing based on

certificates or by prompting the user.  The permissions required by an

application are declared statically in that application, so they can be known

up-front at install time and will not change after that.</p>

<a name="signing"></a>

<h2>Application Signing</h2>