Create entry guidelines

[Hans5958]

Describe the solution

I'm unsure if it is exists, but there should be a guideline for entry contributors to follow. Something like "keep neutral point of view", "use third perspective", "keep in English", and so on.

If there is such guidelines on the wiki, that we can adapt it.

[mxdanger]

Additionally, the description shouldn't be used as a Wikipedia excerpt. I know a lot of entries that copy and pasted for their description.

[Hans5958]

To be fair, this is mentioned on CONTRIBUTING.md. We can change it into something better, along with guidelines.

Usually, the first sentence on Wikipedia is a good example.

atlas-2023/CONTRIBUTING.md

Line 20 in 692b310

- **Description**: A short description that can be understood by somebody not familiar with the topic. Usually, the first sentence on Wikipedia is a good example. If needed, you may include the meta, describing the process of drawing the artwork in the event. To include lengthy, additional information, consider creating a page on [the r/place Wiki](https://place-wiki.stefanocoding.me/).

[twonfi]

Wikipedia probably shouldn't be copy/pasted in the description since that would be plagiarism and also licensing concerns. However, we should be able to use Wikipedia as an example of a good description and start from there.