Chore: Update document for MIPMAP_TEXTURES and MIPMAP_MODES

[SuperSodaSea]

Description of change

Some document update for MIPMAP_TEXTURES and MIPMAP_MODES.

Pre-Merge Checklist

• Documentation is changed or added
• Lint process passed (npm run lint)
• Tests passed (npm run test)

[SuperSodaSea]

@bigtimebuddy Do you think this change is OK for v6.x, or only for v7?

[bigtimebuddy]

Whenever we change default settings that could have some impact on users, I'd consider that breaking (similar to #7974). So I would say v7 for this.

[GoodBoyDigital]

Hey @SuperSodaSea , thanks for the PR!

What would be your thoughts around mipmaps being turned off by default for all textures rather than on? Just thinking about the memory bandwidth we could save people..

[bigtimebuddy]

I'd agree with Mat on this one. The negative memory impact seems substantial enough to keep it as-is.

For the original issue, the user has two very viable options:

1. Enable MIPMAPS by for all textures settings.MIPMAP_TEXTURES = MIPMAP_MODES.ON
2. Only use POT sizes for BitmapFonts

[SuperSodaSea]

That make sence. So should I keep the current default value POW2 or change it to OFF?

[bigtimebuddy]

There are numerous places in Pixi with defaults where we need to balance good rendering with fast performance. This is one of those places. I would vote to keep it as-is (POW2) since I think it's representative of the best practices for Pixi (eg using pow2 spritesheets) over arbitrary sized assets (background images, text). It may not be the best for all scenarios, but that's why we expose a global default and have a local mipmap option on BaseTexture to override per asset.

[SuperSodaSea]

OK, now I reverted the default value to POW2 and only keep the necessary changes in documents.