split documentation to 2 parts

[bung87]

adjust navigation

for beginner: they see features -> learn a bit of nim -> install it try play with

for non-beginner:

click Documentation , check manual and document references directly.

it's a bit weird feeling, click "Documentation" and see "Getting started with Nim" for me.

refs: https://github.com/nim-lang/website/issues/318 likely fit this

maybe add more commit to cover #242 in this PR as well. after investigation it's not a stable choice for putting it into main navigation. but put "Nimble Package Manager" and "Nimble Package Directory" sections together seems to be a improvement to me.

change "Documentation" to "Docs" and "Download" to "Install" make the navigation shorter, might not feel hesitant for adding extro "Packages" link.

and another thing I noticed is "Community" seems to be a stable choice putting into main navigation on language offical sites.

[ringabout]

See also https://github.com/nim-lang/website/pull/276

[bung87]

See also #276

It's really bad idea to me, I don't find reason scroll down full screen to find the "Documentation" links

[ringabout]

cc @narimiran

[narimiran]

It was unified on purpose.

"I have to scroll" is not a real problem, sorry.

[bung87]

that's two click + one scroll.

[rockcavera]

I also didn't like it when everything was unified under the Documentation link. The official documentation is lost among several other links (several that go outside of Nim itself).

I preferred the previous approach, where we had Learn and Documentation.

Edit: see my indignation when the unification happened

[bung87]

“see my indignation when the unification happened” , oh , as a experienced web developer, I'll convincing the ui designer or product manger change the idea. or atleast this won't be done by my hand.

[ZoomRmc]

Clearly, the manual, being the best specs we have, should be treated differently as the main source of truth (besides the actual code).