add delay between bettercap and pwnagotchi starts

[noncenz]

Add a delay as a temporary fix to a race condition between these two services starting

Description

Adds a 2 second sleep before pwnagotchi service starts, to delay deletion of the startup mode override file.

Motivation and Context

This is a temporary fix to issue #61 so that the manual mode caplet runs when appropriate.

• [ X] I have raised an issue to propose this change (required)

How Has This Been Tested?

• Tested manually on a Pi Zero 2W with wifi chipset version 1.
• Tested with v1.7.9 and v.1.8.0 releases

To test:

• Initiate a bluetooth tether to the pwnagotchi with no USB or ethernet connected.
• Tail daemon.log to observe the ip address that the Bettercap service comes up on.
• Toggle between manual and auto modes with the web ui.
• Expect 127.0.0.1 when in auto mode and 0.0.0.0 when in manual.

Types of changes

• [ X] Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [ X] My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• [ X] I've read the CONTRIBUTION guide
• [ X] I have signed-off my commits with git commit -s