More advices and tips from 2 new sources

I added 7 advices and tips from two new sources:

• 47 Tips and Tricks to Become a Better Game Master or Storyteller, by Blackstone Entertainment - https://www.drivethrurpg.com/product/142861/47-Tips-and-Tricks-to-Become-A-Bette...
• How to make a roleplaying game, by Kyle Tam - https://www.dicebreaker.com/categories/roleplaying-game/how-to/how-to-make-rpg