Developer/compiling documentation is not available

Description

There seems to be no up-to-date information how to compile and run KiCad available.

README.md links to Documentation/development/compiling.md, which doesn't exist.

The Wiki links to this, which also doesn't exist.

The contributing page on the website doesn't seem to exist.

I'm mainly asking, because you seem to need to set KICAD_RUN_FROM_BUILD_DIR when running KiCad from IDE (or without installing) to get properly working symbols. There's also the KICAD environment variable, which I'm not sure if you need to set it, to be able to launch pleditor and so on from the main window.

KiCad Version

Application: KiCad

Version: (5.99.0-9829-g074f0432f0), debug build

Libraries:
	wxWidgets 3.1.4
	libcurl/7.71.1 OpenSSL/1.1.1j-fips zlib/1.2.11 brotli/1.0.9 libidn2/2.3.0 libpsl/0.21.1 (+libidn2/2.3.0) libssh/0.9.5/openssl/zlib nghttp2/1.43.0

Platform: Linux 5.10.21-200.fc33.x86_64 x86_64, 64 bit, Little endian, wxGTK, gnome, wayland

Build Info:
	Date: Mar 18 2021 14:28:58
	wxWidgets: 3.1.4 (wchar_t,wx containers) GTK+ 3.24
	Boost: 1.73.0
	Curl: 7.71.1
	ngspice: 33
	Compiler: GCC 10.2.1 with C++ ABI 1014

Build settings:
	KICAD_SCRIPTING=ON
	KICAD_SCRIPTING_MODULES=ON
	KICAD_SCRIPTING_PYTHON3=ON
	KICAD_SCRIPTING_WXPYTHON=ON
	KICAD_SCRIPTING_WXPYTHON_PHOENIX=ON
	KICAD_SCRIPTING_ACTION_MENU=ON
	KICAD_SPICE=ON
	KICAD_STDLIB_DEBUG=OFF
	KICAD_STDLIB_LIGHT_DEBUG=OFF
	KICAD_SANITIZE=OFF