Status of dependencies unclear

[alerque]

I think the dependencies section of the docs needs some help. Somebody recently pointed out that "libx11 is no longer required" with a link to some commit where it was dropped, but the docs are not clear on this subject.

nushell.github.io/book/installation.md

Lines 51 to 69 in 343ee0a

	### Dependencies
	#### Debian/Ubuntu
	You will need to install the "pkg-config" and "libssl-dev" package:
	@[code](@snippets/installation/install_pkg_config_libssl_dev.sh)
	#### RHEL based distros
	You will need to install "libxcb", "openssl-devel" and "libX11-devel":
	@[code](@snippets/installation/install_rhel_dependencies.sh)
	#### macOS
	Using [Homebrew](https://brew.sh/), you will need to install "openssl" and "cmake" using:
	@[code](@snippets/installation/macos_deps.sh)

This section leaves me (as a distro packager for Arch Linuk) with more questions than answers. Why are X11 and XCB libs required on RedHat based distros but not Debian based? Is pkg-config a run time dependency or a build time dependencies? Why does some packaging list curl and bzip2 as dependencies, were these once dependencies now removed, or just undocumented, or just packaging mistakes? Why does macOS need cmake but not other platforms? Experimentally nushell seems to build without XCB or X11 libs, and searching the code base suggests nothing about XCB is used any more.

Can somebody that actually knows clarify what is actually needed at build & run times now and document these as generic dependencies, then comment in the per-distro sections on why those lists vary (e.g. perhaps one was assuming Ubuntu has X11 installed, something that may be true for most workstations but not necessarily servers).

[alerque]

As far as I can tell neither libxcb or libx11 are used or linked during build. Likewise curl and bzip2 are irrelevant. On the other hand openssl (libssl.so and libcrypto.so) is linked, as is zlib (libz.so), so those should be noted as dependencies besides of course glibc, which kind of goes without saying.