add documentation regarding usage of nested docs + git ignore .idea

[steevehook]

Motivation

Glad to contribute to such a nice project 🥇

Test Plan

Added changes to api-doc-markdown then created a new version in order to be able to test

Moderator Edit:

Close #855

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[endiliey]

Thanks for the PR @steevehook

1. There is no need to cut version 1.3.3 for this. All changes in docs will be reflected in next. So it is available for example at localhost:3000/docs/en/next/navigation
2. I've moved it to navigation document instead and simplified the wording

I will let @yangshun or @JoelMarcey see the wordings one more time before merging this

[steevehook]

My pleasure contributing ❤️ @endiliey. Was nice to have a look in the project source, and sorry for the rework. Guess I'll need to familiarize myself with the project to know better where's what. If any other contribution needed I'll be around

[JoelMarcey]

This looks good.

Just curious why we are updating the 1.2.0 version of the doc too?

[endiliey]

@JoelMarcey because this is supposed to be documented for >= 1.2.0 when subdirectories were implemented. (my fault 😢)

[JoelMarcey]

Ok - fair enough. That may be the first time we retroactively added docs for previous versions.