cmake-updates deleting half done stuff, and fixing errors.

[enetheru]

The document originally written by me had some parts that were half finished, some errors I wanted to fix, and some additional things I wanted to address while I was working on it.

Original Problems

• Remove the half done Toolchains section
• fix /s/mutially inclusive/mutially exclusive
• fix the command line examples to be more explicit and solve the error I saw with out of sequence assumptions.

Problems I saw while working on it.

• respect the 80 column rule in prose and in code blocks.
• re-arrange some sections for faster grokking
• be very clear about who the examples are for
• additional usage examples

Original PR

Doc Comment

[Ivorforce]

Looks good to me!

[dsnopek]

Thanks! Looks great to me :-)

[enetheru]

This needs to be squashed yes? do the same rules apply across the godot repositories?

[Ivorforce]

This needs to be squashed yes? do the same rules apply across the godot repositories?

Yep.

[Calinou]

Looks good to me.

I've merged with Squash and merge, so you don't need to squash commits manually when opening PRs on godot-docs. I also used this opportunity to reword the commit message.