Update Notes: v1.2

Update notes v1.1.8 → v1.2:

Enhanced modules, improved usability, fixed some bugs.

• Added a 2D physics module (beta)
  
• Added examples to the "Physics" category
  
• Fixed a random seeding issue under multi-threading environment
  
• Fixed a crash bug of the `Resources.load(...)` function when argument is invalid
  
• Fixed a newline issue of content text in the document viewer