Add the default storyboard template to docs

[SethuSenthil]

Is your feature request related to a problem? Please describe.
Chances are people who are initially running into this package have already tried other ways of setting the Splash Screen. This causes a problem when the developer has already modified the storyboard on iOS Xcode project, they will likely run into the error

Not able to find "LaunchImage" in LaunchScreen.storyboard. Image for splash screen not updated. Did you modify your default LaunchScreen.storyboard file?

Describe the solution you'd like
Add an option to override and replace the splash storyboard file with the default boilerplate storyboard file so they can proceed.

Describe alternatives you've considered
Until this becomes a feature, a link to the default storyboard file in the documentation would be helpful so the developers can manually replace the file.

Additional context
This would be a time-saving enhancement, instead of wasting time creating a new Xcode project or going through Github commits to find the compatible storyboard file, it will automatically be replaced or have a link to the default file in the docs.

Link to the autogenerated file referenced in this issue: LaunchScreen.storyboard.zip

[jonbhanson]

I will push an update soon that will fix this.