Godot-docs: Remove unnecessary uses of "simple", "simply", and "easy"

[fdmarcin]

Issue description:
Currently, these words appear this many times in .rst files, (excluding class... files):

| Word | Occurrences |
|---|---|
|simple | 201 |
|simply | 89 |
|easy | 61 |
|~please~ | ~58~ |

• ~please: in my opinion, it's unnecessary almost in all cases - it makes the writing more _polite_, but it makes it less easy to read.~
• simple / simply / easy: it's often easy to misjudge if a task is really _easy_ or a concept _simple_, and in cases when we say it is, but it turns out the opposite for the reader, they might feel frustrated or incompetent. Approximately 50-80% of the time, it's safe to edit these out too. See _Don't Say Simply_ (article or talk) for context.

Proposal:
I could pick up this task, but first wanted to get your opinion :)

[fdmarcin]

Ah, I've just found the docs writing guidelines too 😃

Ban these 8 words: obvious, simple, basic, easy, actual, just, clear, and however

[Calinou]

I think it's better to leave in most occurrences of "please" (unless they're repeated too often in a single page), but feel free to open a pull request to remove occurrences of "simple", "simply" and "easy".

[fdmarcin]

@Calinou Okay, thanks! I edited the title and description of this. If you want, you can assign me to this issue.

[Xrayez]

"Please" is more like an apology for making you do a workaround, so justifiable IMO. 😛

Regarding "simple" and "simply"