Removed redundancy and better wording.

[lgmsantos]

Found some redundancy while following this guide.

[Piralein]

The note was added by #6781 and #7232, because it was often missed by people following the introduction.
I don't have a strong opinion about how it should be stated.

The initial request to remove it is in 05 - The main game scene.
Maybe it should be added as a warning above the Now you're ready to play! Click the "Play the Project" button. as a reminder and removed for the remaining page.

[mhilbrunner]

Thanks for contributing! I've merged #8437, which aims to fix this and supersedes this PR. Thanks for bringing this to our attention and taking the time to contribute :)